HomeMy WebLinkAboutRS_rockery_report_20161101_v1.pdf Rockery Wall Recommendations
Thunder Hills Creek
Sewer Alignment
Grant Avenue South – I 405 Area
Renton, Washington
November 1, 2016
ROCKERY WALL RECOMMENDATIONS
THUNDER HILLS CREEK
SEWER ALIGNMENT
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Table of Contents
1.0 INTRODUCTION .................................................................................................................. 1
2.0 PROJECT DESCRIPTION ...................................................................................................... 1
3.0 SITE DESCRIPTION .............................................................................................................. 1
4.0 SUBSURFACE DATA ............................................................................................................ 3
4.1.1 Site Investigation Program ................................................................................... 3
5.0 SOIL AND GROUNDWATER CONDITIONS ......................................................................... 4
5.1.1 Area Geology .................................................................................................... 4
5.1.2 Soil Conditions .................................................................................................... 4
6.0 GEOLOGIC HAZARDS ...................................................................................................... 6
6.1.1 Landslide Hazard................................................................................................ 6
6.1.2 Erosion Hazard .................................................................................................... 7
6.1.3 Seismic Hazard ................................................................................................... 8
7.0 DISCUSSION ....................................................................................................................... 8
7.1.1 General ............................................................................................................... 8
8.0 RECOMMENDATIONS ........................................................................................................ 9
8.1 SITE PREPARATION ............................................................................................................. 9
8.2 TEMPORARY EXCAVATIONS ............................................................................................10
8.3 EROSION AND SEDIMENT CONTROL ...............................................................................11
8.4 ROCKERY WALLS ..............................................................................................................12
8.5 UTILITIES ............................................................................................................................19
8.6 GROUNDWATER INFLUENCE ON CONSTRUCTION .........................................................20
8.7 ACCESS ROADWAY CONSTRUCTION .............................................................................20
9.0 CONSTRUCTION FIELD REVIEWS .......................................................................................21
10.0 CLOSURE ..........................................................................................................................21
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Table of Contents (Continued)
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LIST OF APPENDICES
Appendix A — Statement of General Conditions
Appendix B — Figures
Appendix C — Boring Logs & Rockery Spreadsheets
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SEWER ALIGNMENT
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1.0 Introduction
In accordance with authorization by the City of Renton, Stantec has completed a geotechnical
report with rockery wall recommendations for the Thunder Hills Creek Sewer Alignment project
located in Renton, Washington.
The purpose of this report was to summarize the known and anticipated geologic conditions
within the project area and provide recommendations for rockery wall construction, mass
grading, roadway construction, utility backfill, and rock buttress placement.
The scope of work for the study consisted of multiple levels of field investigations and document
reviews followed by engineering analyses to prepare this report. Recommendations presented
herein pertain to various geotechnical aspects of the proposed project, including grading, utility
placement, utilities, rockery wall construction, and rock buttressing.
2.0 Project Description
The project consists of rehabilitating (lining) the existing sewer line along Thunder Hills Creek,
placement of about 1,500 feet of new 12 inch diameter HDPE sewer pipe, 6 new sanitary sewer
manholes (SSMH), re-grading of the existing access roadway, and placement/construction of
rockery walls and rock buttresses. New manholes will be placed to depths ranging from 7 to 12
feet below existing site grades.
The access roadway improvements include apron widening at the south end of the alignment
(Grant Avenue S.), a turnaround at Stations 7+50 to 8+40, and hammerhead improvements near
Station 16+00. North of about Station 7+50, the access roadway will be re-graded to allow
access with small equipment.
Re-grading and slope modifications are proposed locally along the alignment. In general, these
include cuts of up to 4 feet and fills on the order of 2 feet or less.
3.0 Site Description
The Thunder Hills Creek project area is located between I -405 and Grant Avenue South, just east
of the Berkshire Apartment Home development (Figure 1). The site area includes existing
developed areas along the east side of Thunder Hills Creek south of about Station 13+40 and
along the west side of Thunder Hills Creek north of Station 12+50.
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In general, the area of proposed development will be limited to the valley bottom along existing
roadway alignments and adjacent embankments. Figures 2 through show the general site
layout, wall locations, and utility alignment.
The site consists of the existing sewer interceptor alignment through the Thunder Hills Creek valley
along with a gravel improved access roadway located adjacent to the stream for much of the
alignment. The access roadway has been damaged significantly by soil movement and erosion
near Station 6+50 (Figure 2). North of this location, the roadway is improved (partially) with
quarry rock north to a flat area near I-405.
South of Station 7+50, variable amounts of sediment are present in the stream channel. North of
this area, the stream has incised into the underlying sandstone (Renton Formation). Four to 12
inch sized quarry rock is present in the stream bed and banks in many areas. Larger quarry rock,
generally ½ to 4 man sized basalt, has been used to stabilize the stream banks and/or to prevent
ongoing stream erosion. Specifically in the vicinity of Station 6+00, large quarry rock has been
used to fill the stream channel.
Rock filled gabion walls, generally 4 to 6 feet in height, are located between the access
roadway/path and Thunder Hills Creek north of Station 5+50 and locally upstream along the east
side of the stream. For the most part, the gabion baskets have deteriorated significantly and in
places the walls are somewhat overturned. The gabion walls appear to have limited
functionality as retaining structures for the roadway and sewer line.
The slopes extending downward into the Thunder Hills Creek valley between Stations 0+25 and
6+40 are very steep, with magnitudes of 100 to 150 percent. There are localized slope areas that
are near vertical (200 percent magnitude) to overturned due to excavation, sloughing, and/or
landslide activity. Several rockeries are located along the east and west sides of the access
roadway between Stations 4+80 and 6+50. The rockeries are comprised of 1 to 2 man sized
basalt and are up to 7 feet in height. The rockeries are loosely constructed.
There is evidence that shallow landslide activity occurs periodically along portions of the slope
west of the access roadway north of Station 5+50. Several large, but shallow, landslides have
occurred within the last several years north of Station 3+50. The slides appear to consist of the
upper colluvium (1 to 4 feet thick) sliding off of the underlying sandstone. The slides extend
upslope between 10 and 50 feet and are up to 70 feet wide.
South of Station 13+40, a majority of the natural slopes along the east side of the stream have
moderate magnitudes ranging from 15 to 40 percent. Locally along the east side of the access
road, there are steep to undermined excavations up to 10 feet in height. These slopes are
generally 100 percent or steeper in magnitude. Exposed soils are consistent with glacial till.
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The site is bordered to the north by I -405, to the west by the Berkshire Apartment Homes, to the
east by undeveloped land (easements) and single family residences, and to the south by
Thunder Hills Creek, easements, and residential developments.
4.0 Subsurface Data
4.1.1 Site Investigation Program
The geotechnical field investigation program was completed on October 17th and 20th, 2014
and included drilling and sampling four hollow stem auger borings drilled by a Stantec
subcontractor using a limited access drill rig. The borings were located at or near pre-
determined locations and extended approximately 5 to 25 feet below the existing site grades.
Additional hand borings were excavated on August 12, 2016 to verify shallow soil conditions
where rockery walls may be constructed.
The soils encountered were logged in the field during the exploration and are described in
accordance with the Unified Soil Classification System (USCS). Disturbed soil samples were
obtained by using a 140 pound hammer free falling a vertical distance of 30 inches for the
borings.
The summation of hammer-blows required to drive the sampler the final 12 -inches of an 18-inch
sample length is defined as the Standard Penetration Resistance, or N-value for a 140 pound
hammer and 2 inch outside diameter split spoon sampler.
The uncorrected blow count is presented graphically on the boring logs in Appendix C. The
resistance, or “N” value, provides a measure of the relative density of granular soils and the
consistency of cohesive soils. Our report discussions regarding soil density as well as engineering
parameters are based on the N values.
A Stantec field representative directed the drilling program, collected disturbed soil samples
from split spoon sampler tubes, classified the encountered soils, kept a det ailed log of each
auger hole, and observed and recorded pertinent site features.
The results of the drilling and sampling are presented on the boring logs enclosed in Appendix C.
We also reviewed six boring logs from a geotechnical investigation conducted by Soil and
Environmental Engineers, Inc. (S&EE) in 2011. This report was conducted to develop solutions to
retain/protect the existing sewer line in the lower portion of the Thunder Hills Creek valley.
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5.0 Soil and Groundwater Conditions
5.1.1 Area Geology
The site lies within the Puget Lowland. The lowland is part of a regional north -south trending
trough that extends from southwestern British Columbia to near Eugene, Oregon. North of
Olympia, Washington, this lowland is glacially carved, with a depositional and erosional history
including at least four separate glacial advances/retreats.
The Puget Lowland is bounded to the west by the Olympic Mountains and to the east by the
Cascade Range. The lowland is filled with glacial and nonglacial sediments consi sting of
interbedded gravel, sand, silt, till, and peat lenses.
The Geologic Map of King County, indicates that the site is located near the contacts between
Vashon Glacial Till and Tertiary Bedrock.
Vashon Glacial Till is typically characterized by an unsorted, nonstratified mixture of clay, silt,
sand, gravel, cobbles and boulders in variable quantities. These materials are typically dense
and relatively impermeable. The poor sorting reflects the mixing of the materials as these
sediments were overridden and incorporated by the glacial ice.
Tertiary Bedrock in this area consists of the Renton Formation. The Renton Formation includes
feldspathic fine to medium grained sandstone with beds of coal, carbonaceous siltstone, and
claystone. Tertiary Bedrock locally outcrops south of I -90 and the Seattle Fault Zone due to uplift
associated with seismic activity.
5.1.2 Soil Conditions
Details of the encountered soil conditions are presented on the boring logs in Appendix C. The
detailed soil description on these logs should be referred to in preference to the generalized
descriptions below.
Boring B-1
In Boring B-1, we encountered approximately 6 inches of topsoil and vegetation underlain by
approximately 5 feet of medium dense to dense, silty-fine to medium grained sand with variable
amounts of gravel and debris (Fill). This layer was underlain by stiff to very stiff silt with variable
amounts of sand and woody debris (Fill). The silt layer was underlain by stiff silt with variable
amounts of sand, gravel, and trace amounts of woody debris (Highly Weathered Renton
Formation). These materials were underlain by medium dense, silty-sand with clasts of
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weathered sandstone (Weathered Renton Formation), which continued to the termination
depth of the boring.
Borings B-2 and B-3
In Borings B-2 and B-3, we encountered approximately 10 to 12 inches of vegetation and topsoil
underlain by approximately 5 feet of medium dense, silty-fine to medium grained sand with
variable amounts of gravel (Fill). This layer was underlain by dense to very dense, silty-fine to
medium grained sand with variable amounts of gravel (Glacial Till), which continued to the
termination depths of these borings.
Boring B-4
In Boring B-4, we encountered approximately 8 inches of angular rock underl ain by
approximately 4 feet of loose to medium dense, silty-fine to medium grained sand with variable
amounts of gravel (Fill). This layer was underlain by hard sandstone (Renton Formation), which
continued to the termination depth of the boring (refusal).
Observed Soil Conditions South of Station 13+40
South of Station 13+40, the shallow subsurface soils generally include up to 2 feet of vegetation
and topsoil underlain by 2 to 4 feet of loose to medium dense, silty-fine to medium grained sand
with variable amounts of gravel (Weathered Glacial Till). This layer is underlain by dense to very
dense, silty-fine to medium grained sand with variable amounts of gravel (Glacial Till).
There are many open cuts along the east side of the access roadway. We probed the exposed
soils at many locations and encountered medium dense to dense glacial till.
Groundwater
At the time of our investigation, groundwater was encountered in Boring B -4 at approximately
4.5 feet below the existing site grade. Groundwater was not encountered in any of the other
explorations at the date of our investigation.
We anticipate that groundwater in the Thunder Hills Creek valley is primarily influenced by area
streams and surface water runoff/infiltrating surface waters . There are areas of the site near I-405
where surface water and groundwater is at the same level (ground surface) and areas where
groundwater is not encountered below stream depths due to stream channel confinement
within the Renton Formation sandstone. Groundwater may be found perched within upper
loose sediments or fill, or between weathered and unweathered geologic units.
There are numerous drains extending downslope toward the access road from the east south of
Station 13+40. At the time of our visit, no water was observed flowing from these pipes; however,
there could be runoff during the wetter months of the year.
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We anticipate low to moderate seasonal seepage from the valley/channel sidewalls
contributing to the overall volume in Thunder Hills Creek. A majority of volume contribution to
the stream is from drainage conveyance from nearby residential developments and tributary
streams.
Water levels at the time of the field investigation may be different from those encountered
during the construction phase of the project.
6.0 Geologic Hazards
6.1.1 Landslide Hazard
Typically, slopes with magnitudes greater than about 40 percent and vertical relief of at least 10
feet can be classified as geologically hazardous (steep slope/landslide hazards). Many of the
slopes that extend into the Thunder Hills Creek valley meet these criteria.
North of Station 6+00
There are many areas north of Station 6+00 that range in magnitude between 80 and 150
percent. These slopes are covered with up to several feet of weathered soils (colluvium) and
are mostly vegetated with trees and undergrowth.
We observed several relatively recent landslides in the area north of Station 2+50, primarily along
the steep slopes along the west side of Thunder Hills Creek. These slides appear to be relatively
shallow, consisting of colluvium sliding off of the underlying sandstone. We did not observe
evidence of deep-seated landslide activity within the valley.
It is our opinion that the contributing causes for landslide activity in the north portion of Thunde r
Hills Creek valley include previous excavations for access roadway construction, surface water
and spring/seep activity along the slopes, and the presence of loose colluvium over relatively
impermeable, hard sandstone at steep inclinations.
Slope stability analyses are not warranted for the upper portions of the slopes extending into the
Thunder Hills Creek valley as their relative stability can be visually assessed.
Factors that influence the relative factors of safety along the slope areas include surface water ,
vegetation and root systems, colluvium/fill density and thickness, and slope magnitude. We
anticipate lower factors of safety and higher probability of landslide activity to occur from
approximately November to May when precipitation is highest.
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South of Station 6+00
In general, the slope magnitudes south of Station 6+00 range from 30 to 100 percent. There are
local excavations along the existing roadway that are near vertical to slightly overturned
(undercut). These excavations are up to 8 feet in height and some minor sloughing was
observed. The dense glacial till that underlies these areas are typically resistant to global
instability. The proposed rockery construction and/or re-grading of slope cuts will reduce the
erosion and sloughing potential of these areas.
6.1.2 Erosion Hazard
The Natural Resources Conservation Services (NRCS) maps for King County indicate that the
project area and directly adjacent side slopes are underlain by Alderwood and Kitsap soils (very
steep), Alderwood gravelly sandy loam (8 to 30 percent slopes) and Beausite gravelly sandy
loam (15 to 30 percent slopes). Since the project is located within an actively incising stream
environment adjacent to very steep slope areas, all soils should be considered to have “Severe”
to “Very Severe” erosion potential.
It is our opinion that soil erosion potential at this project site, if grading activities are proposed,
can be reduced through surface water runoff control and local removal of problem soil areas
(discussed in Section 8.1). Typically erosion of exposed soils will be most noticeable during
periods of rainfall and may be controlled by the use of normal temporary erosion control
measures, such as silt fences, hay bales, mulching, control ditches and diversion trenches. The
typical wet weather season, with regard to site grading, is from October 31st to April 1st. Erosion
control measures should be in place before the onset of wet weather.
While erosion of the sandstone that underlies the site between Stations 0+00 and 5+50 will oc cur
at a low to very low rate over the lifespan of the sewer line (80 years), large storm events and
long term erosion of the sandstone could erode the existing gabion walls and slope between the
stream and sewer line. To reduce adverse effects of soil and slope erosion caused by Thunder
Hills Creek, permanent erosion prevention systems should be constructed. Large rock buttressing
embedded into the unweathered sandstone should provide adequate protection for the sewer
line and access roadway.
6.1.3 Seismic Hazard
We encountered generally medium dense to very dense soils and locally soft rock at the project
site. The overall subsurface profile corresponds to a Site Class D as defined by Chapter 20 of
ASCE 7 (Table 20.3-1) and referenced in Table 1613.3.2 of the 2015 International Building Code
(2015 IBC). A Site Class D applies to an overall profile consisting of medium dense/stiff to very
dense/hard materials within the upper 100 feet.
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Areas of the site, including areas directly underlain by soft bedrock (sandstone), would be
considered as a Site Class C, soft rock profile. We do not anticipate the need to utilize seismic
parameters from this profile as part of the currently proposed project and therefore they have
not been included.
We referenced the U.S. Geological Survey (USGS) Earthquake Hazards Program Website (seismic
calculator) to obtain values for SS, S1, Fa, and Fv. The USGS website includes the most updated
published data on seismic conditions. The site specific seismic design parameters and adjus ted
maximum spectral response acceleration parameters are as follows:
PGA (Peak Ground Acceleration, in percent of g)
32.24 (10% Probability of Exceedence in 50 years)
62.52 (2% Probability of Exceedence in 50 years)
SS 141.10% of g
S1 48.30% of g
Additional seismic considerations include liquefaction potential and amplification of ground
motions by soft/loose soil deposits. The liquefaction potential is highest for loose sand with a high
groundwater table. The dense to very dense, glacially consolida ted materials and bedrock that
underlie the site have a very low potential for liquefaction.
7.0 Discussion
7.1.1 General
It may not be economically feasible to construct preventative structures to eliminate shallow
landslide activity which originates higher up the steep slopes above the proposed/existing
access roadway in the north portion of the site. At a minimum, we recommend performing
remedial excavation work to reduce the likelihood and adverse effects of shallow colluvial slides
on the proposed/existing access roadway along with rockery wall construction, and select
hazardous tree removal.
Rock buttresses should be constructed between the access roadway and stream within the
north portion of the alignment to prevent erosion/undercutting of the roadway and sewer line
by Thunder Hills Creek over the design lifespan of the sewer line (approximately 80 years). These
would replace existing gabion walls which are failing in places.
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Rockery walls may be constructed along localized steep excavations along the east side of the
access roadway may be re-graded or faced with rockery walls to reduce sloughing and erosion
over time. A combination of rockery walls with re -graded back slopes is suitable in lieu of
constructing very tall rockery walls or extending lower magnitude permanent slopes beyond the
construction and/or easement limits.
8.0 Recommendations
8.1 SITE PREPARATION
In general, site preparation should consist of vegetation and topsoil removal from proposed
excavation/improvement areas. Based on observations from the site investigation program and
site reconnaissance work, it is anticipated that the stripping depth will generally be less than 12
inches where topsoil and vegetation are present. The excavated material is not suitable as
structural fill but could be used as fill material in non-settlement sensitive areas such as
landscaping. In these non-settlement sensitive areas, the fill should be placed in maximum 12
inch thick lifts that should be compacted to at least 90 percent of the modified proctor (ASTM D
1557 Test Method) maximum dry density.
As needed, leaning trees and other trees designated as hazard trees located in critical areas,
may be removed during site preparation. It may be useful to leave root systems in place
depending on the location of the hazard trees. We can provide recommendations on which
trees are suitable for full removal or partial removal upon request.
Native soils are generally considered suitable for use as structural fill provided they are within 3
percent of the optimum moisture content and free of deleterious materials. It should be noted
that these materials are typically suitable for structural fill only during the summer months and are
highly moisture sensitive due to their fines content.
Imported structural fill should consist of a sand and gravel mixture with a maximum grain size of 3
inches and less than 5 percent fines (material passing the U.S. Standard No. 200 Sieve).
Structural fill should be placed in maximum lift thicknesses of 12 inches and should be
compacted to a minimum of 95 percent of the modified proctor maximum dry density, as
determined by the ASTM D 1557 test method.
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8.2 TEMPORARY EXCAVATIONS
Based on our understanding of the project, grading associated with access road construction
will include cuts on the order of 4 feet or less. Utility excavations may be up to 12 feet below
existing grades; however, we anticipate that temporary shoring will be used for these
excavations. If any utility excavations will be openly excavated, we recommend they be sloped
no steeper than 1H:1V in medium dense native soils and 3/4H:1V in dense to very dense native
soils. Recommendations for temporary excavations for rockery and buttress construction are
addressed separately in Section 8.4.
If an excavation is subject to heavy vibration or surcharge loads, we recommend that the
excavation be sloped no steeper than 1.5H:1V and 1H:1V, respectively as above, where room
permits. If groundwater is encountered, lower declinations may be required.
In general, excavations in slightly weathered sandstone may be stable up to a vertical
condition; however, we do not anticipate the need to excavate into sandstone other than
removing loose colluvium from existing slopes along the west side of the proposed access
roadway. In these areas, we recommend scraping the loose materials and any loose sandstone
that readily comes free from the rock faces only. Again, Stantec should be on site to observe
the conditions during construction and provide location-specific recommendations.
All temporary cuts should be in accordance with the Washington Administrative Code (WAC)
Part N, Excavation, Trenching, and Shoring. The temporary slopes should be visually inspected
daily by a qualified person during construction activities and the inspections should be
documented in daily reports. The contractor is responsible for maintaining the stability of the
temporary cut slopes and reducing slope erosion during construction.
The temporary cut slopes should be covered with visqueen to help reduce erosion during wet
weather, and the slopes should be closely monitored until the permanent retaining systems or
slope configurations are complete. Materials should not be stored or equipment operated
within 10 feet of the top of any temporary cut slope.
Soil conditions may not be completely known from the geotechnical investigation. In the case
of temporary cuts, the existing soil conditions may not be completely revealed until the
excavation work exposes the soil. Typically, as excavation work progresses , the maximum
inclination of the temporary slopes will need to be re -evaluated by the geotechnical engineer
so that supplemental recommendations can be made. Soil and groundwater conditions can
be highly variable. Scheduling for soil work will need to be adjustable, t o deal with
unanticipated conditions, so that the project can proceed and required deadlines can be met.
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If any variations or undesirable conditions are encountered during construction, Stantec should
be notified so that supplemental recommendations can be made. If room constraints or
groundwater conditions do not permit temporary slopes to be cut to the maximum angles
allowed by the WAC, temporary shoring systems may be required. The contractor should be
responsible for developing temporary shoring systems, if needed. We recommend that Stantec
and the project structural engineer review temporary shoring designs prior to installation, to verify
the suitability of the proposed systems.
8.3 EROSION AND SEDIMENT CONTROL
Erosion and sediment control (ESC) is used to reduce the transportation of eroded sediment to
wetlands, streams, lakes, drainage systems, and adjacent properties. Erosion and sediment
control measures should be implemented and these measures should be in general
accordance with local regulations. At a minimum, the following basic recommendations should
be incorporated into the design of the erosion and sediment control features for the site:
Schedule the soil, foundation, utility, and other work requiring excavation or the disturbance
of the site soils, to take place during the dry season (generally June through September).
However, provided precautions are taken using Best Management Practices (BMP’s), certain
grading activities can be completed during the wet season (generally October through
April).
All site work should be completed and stabilized as quickly as possible.
Additional perimeter erosion and sediment control features may be required to reduce the
possibility of sediment entering the surface water. This may include additional silt fences, silt
fences with a higher Apparent Opening Size (AOS), construction of a berm, or other filtration
systems.
Any runoff generated by dewatering discharge should be treated through construction of a
sediment trap if there is sufficient space. If space is limited, other filtration methods will need
to be incorporated.
Specifically for this project, site grading should only be performed during the summer months
(late June through mid-September) when the creek is at it lower levels and surface waters w ill be
less prevalent. Additional erosion control measures will likely be required between the proposed
roadway and Thunder Hills Creek during construction due to the presence of wetlands.
There are areas where loose colluvium overlies hard sandstone at s teep angles between Station
0+50 and 4+00. The removal of soils and trees from site slopes should be observed by the
geotechnical engineer as slope stability above these locations could be adversely affected.
Replacement of loose soils with quarry rock may be warranted. In general, we recommend
removal of trees and colluvium only where necessary and with geotechnical oversight.
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8.4 ROCKERY WALLS
Rockery walls are not considered as engineered gravity retaining walls mainly because the
structure is not an integral as the rocks are just siting and they are not structurally connected to
each other. They generally function as erosion protection for the materials they face that are
themselves stable, which should be dense to very dense soils with adequate fines, p referably
glacially consolidated materials in the region. Based on our observations at the site, the
underlying materials appear to consist of dense glacial till and/or hard sandstone.
The shallow soil conditions along the proposed alignment and adjacent roadway areas
generally consist of loose to medium dense weathered glacial till overlying dense to very dense
unweathered glacial till. Sandstone is locally exposed north of about Station 6+00. Because of
the soil density, rockery walls are generally suitable to protect roadway excavations from
erosion. Glacial till or bedrock are in our opinion, the only geologic units in the Puget Sound
region suitable for rockery facing.
At this site, rockery walls will be up to 10 feet in exposed height. We recommend a minimum of
12 inches of embedment for walls between 4 and 10 feet tall and 6 inches for walls with exposed
heights of 4 feet or less. All walls should have a minimum batter of 6V:1H (vertical to horizontal)
and be backfilled with 2 to 4 inch sized angular quarry rock. Rockery drainage
recommendations can be found below.
All rockeries should be constructed per the Associated Rockery Contractors (ARC) guidelines
(http://www.ceogeo.org/schedule/09244404pm_Current%202013%20ARC%20Rockery%20Constr
uction%20Guidelines.pdf ) with geotechnical monitoring of the keyway excavation, drainage,
rock placement, backfill, and excavation work by the geotechnical engineer.
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Wall Locations
Rockery walls will be necessary locally along the upslope side of the access roadway between
Stations 4+40 and 27+35. During our field assessments, we observed undermined cuts and local
near-vertical excavations along the upslope (east) side of the access roadway at several
locations. The roadway will be widened up to several feet during the construction phases of the
project and these excavations should be protected from erosion. General locations of rockery
walls are as follows:
Wall
Designation
Approximate
Stationing
Estimated Height
Range
No. 1 4+40 to 6+70 Up to 8 Feet
No. 2 7+50 to 8+45 Up to 10 Feet
No. 3 13+40 to 14+25 Up to 6 Feet
No. 4 16+85 to 20+20 Up to 10 Feet
No. 5 20+55 to 24+60 Up to 10 Feet
No. 6 25+05 to 27+35 Up to 8 Feet
Field conditions may warrant alterations in wall heights, slope inclinations above the walls,
rockery lengths, and backfill requirements. Typically, these adjustments are relatively minor and
can be made in the field by the contractor and geotechnical engineer/personnel.
Rockery Wall Design
Our rockery design recommendations refer to various rock sizes. The Washington State
Department of Transportation (WSDOT) uses the following table when referring to larger size rocks
and boulders:
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Rock Size Rock Weight Ave. Dimensions
Half Man 25 - 50lbs 6” - 12"
One Man 50 - 200lbs 12" - 18"
Two Man 200 - 700lbs 18" - 28"
Three Man 700 - 2,000lbs 28" - 36"
Four Man 2,000 - 4,000lbs 36" - 48"
Five Man 4,000 - 6,000lbs 48" - 54"
Six Man 6,000 - 8,000lbs 54" - 60"
Design Parameters
The following soil parameters were used in rockery design calculations:
Soil Type Friction Angle Cohesion Unit Weight
Retained Soils (Glacial Till) 36 degrees 0 psf 120 pcf
Foundation Soils (Glacial Till) 36 degrees 0 psf 120 pcf
psf = pounds per square foot
pcf = pounds per cubic foot
A unit weight of 155 pcf was used for large rocks. The designs also utilized an assumed wall
batter of 6V:1H (Vertical to Horizontal) and variable back slope angles up to a maximum of 2H:1
(Horizontal to Vertical).
The following tables indicate recommended minimum rock sizes for use in rockery wall
construction for various wall heights and back slope angles. All heights shown in the tables are
for the exposed wall heights, not total height. All walls over 4 feet in exposed height should have
a minimum 12 inch embedment into the native soils.
ROCKERY WALL RECOMMENDATIONS
THUNDER HILLS CREEK
SEWER ALIGNMENT
November 1, 2016
15
4 Feet Tall Rockery Wall
Back Slope Angle Base Rock Size (Min. in Feet) Top Rock Size (Min. in Feet)
Level to 4H:1V 2 1.5
4H:1V to 2.5H:1V 2.5 2
2H:1V 2.5 2
5 Feet Tall Rockery Wall
Back Slope Angle Base Rock Size (Min. in Feet) Top Rock Size (Min. in Feet)
Level to 4H:1V 2.5 2
4H:1V to 2.5H:1V 2.5 2
2H:1V 3 2
6 Feet Tall Rockery Wall
Back Slope Angle Base Rock Size (Min. in Feet) Top Rock Size (Min. in Feet)
Level to 4H:1V 3 2
4H:1V to 2.5H:1V 3 2.5
2H:1V 3.5 2.5
ROCKERY WALL RECOMMENDATIONS
THUNDER HILLS CREEK
SEWER ALIGNMENT
November 1, 2016
16
7 Feet Tall Rockery Wall
Back Slope Angle Base Rock Size (Min. in Feet) Top Rock Size (Min. in Feet)
Level to 4H:1V 3.5 2.5
4H:1V to 2.5H:1V 3.5 2.5
2H:1V 4 2.5
8 Feet Tall Rockery Wall
Back Slope Angle Base Rock Size (Min. in Feet) Top Rock Size (Min. in Feet)
Level to 4H:1V 3.5 3
4H:1V to 2.5H:1V 3.5 3
2H:1V 4 3
9 Feet Tall Rockery Wall
Back Slope Angle Base Rock Size (Min. in Feet) Top Rock Size (Min. in Feet)
Level to 4H:1V 3.5 2.5
4H:1V to 2.5H:1V 4 3
2H:1V 4.5 3.5
ROCKERY WALL RECOMMENDATIONS
THUNDER HILLS CREEK
SEWER ALIGNMENT
November 1, 2016
17
10 Feet Tall Rockery Wall
Back Slope Angle Base Rock Size (Min. in Feet) Top Rock Size (Min. in Feet)
Level to 4H:1V 4 3.5
4H:1V to 2.5H:1V 4 3.5
2H:1V 5 3.5
Wall Subgrade Preparation
To prepare the wall areas for construction, all vegetation, organic surface soils, and other
deleterious materials including any existing structures, foundations or abandoned utility lines
should be stripped and removed from the keyway areas.
Rockery keyways should be excavated to the level of medium dense or firmer native soils. If
excessively soft or yielding areas are present, and cannot be stabilized in place by compaction,
they should be cut to firm bearing soil and filled to grade with structural fill. If the depth to
remove the unsuitable soil is excessive, we should be contacted to provide recommendations as
necessary for the successful completion of the walls, or to re-evaluate the wall designs based on
actual site conditions.
Quarry rock (2-8 inches in size) is recommended as fill behind rockery walls. We recommend a
minimum width of 1.5 feet of quarry rock be placed between the rockery and native cut face.
Wall Drainage
To guard against hydrostatic pressure development, drainage must be installed behind the
walls. Typically, rockery walls are backfilled with clean angular rock (2-4 quarry rock) which
extends from the base to the top of the wall and 18 to 24 inches in width. In addition to this rock
placement, a drainage collector system consisting of 4-inch perforated PVC pipe should be
placed behind the wall to provide an outlet for any accumulated water.
Throughout the project, it is paramount that the geotechnical engineer periodically monitors all
rockery walls constructed against cuts or fills exceeding 4 feet in height. It is important for the
engineer to verify that the construction and materials meet the original geotechnical
recommendations and specifications. The geotechnical engineer should also develop a
ROCKERY WALL RECOMMENDATIONS
THUNDER HILLS CREEK
SEWER ALIGNMENT
November 1, 2016
18
monitoring plan for visiting the site. For instance, ARC (1991) recommends for a single tiered
rockery wall that is less than 50 feet in length should require a minimum of at least one visit along
with daily inspections by a project engineer/geologist. The geotechnical engineer must
maintain records of the nature and condition of the wall under observation.
In addition, the engineer should verify the soundness of the rocks selected for the rockery wall by
striking the selected rocks with a geology hammer. A loud ring suggests strong competent rock.
Conversely, a dull thud will suggest poor rock not fit for a rockery wall.
Rock Buttresses
As needed, primarily in the area between Stations 2+00 to 5+50, rock buttresses may be utilized
to support the access roadway and prevent lateral pipe movements and/or
erosion/undercutting of the sewer line. However, any type of retaining structure will only be
effective if they are embedded into the underlying sandstone. In other words, fill material or soil
deposits that are used to support retaining structures could be easily eroded by t he stream
during storm events when flows are high in volume and velocity, potentially causing the
structures to fail (as observed with the current gabion walls).
Rock buttresses may be used to protect the existing sewer line and access roadway from stream
erosion and sloughing in the north portion of the project site. In general, buttresses should be
constructed between the access path/roadway and stream channel. Existing dilapidated
gabion structures should be removed as part of grading activities. Much of the angular rock in
the gabion baskets may be utilized between large rocks in the buttresses.
We recommend that quarry rock used as buttress materi al be 4-man sized or larger. Condition-
specific recommendations may be made during construction by Stantec if subsurface
conditions warrant.
In general, buttressing should consist of the following:
Gabion wall removal
Loose soil removal and temporary excavation creation (generally between 3/4H:1V and
1.5H:1V)
Excavation of a keyway at the toe of the buttress (at least 18 inches into underlying
dense soils or weathered sandstone)
Placement of large angular basalt with interstitial quarry rock (as void fill)
Stantec should be on site to observe gabion removal, keyway excavations, and rock
placement.
ROCKERY WALL RECOMMENDATIONS
THUNDER HILLS CREEK
SEWER ALIGNMENT
November 1, 2016
19
8.5 UTILITIES
Sewer line trenches should be excavated according to accepted engineering practices
following OSHA (Occupational Safety and Health Administration) standards, by a contractor
experienced in such work. The contractor is responsible for the safety of open trenches. Traffic
and vibration adjacent to trench walls should be reduced; cyclic wetting and drying of
excavation side slopes should be avoided. Depending upon the location and depth of some
utility trenches, groundwater flow into open excavations could be experienced, especially
during or shortly following periods of precipitation.
In general, silty soils were encountered at shallow depths in the explorations at this site. At this
site, these soils have variable density and minimal cohesion and will have a tendency to cave or
slough in excavations. Shoring or sloping back trench sidewalls is required within these soils. If
sewer line excavations extend deep enough to encounter sandstone (not anticipated), rock
chipping/breaking equipment would likely be required to allow for excavation. Excavations in
sandstone should be adequately safe to remain vertical for a significant amount of time.
All utility trench backfill should consist of imported structural fill. Certain on site soils may be
suitable for use as backfill in landscaping areas during the summer months; however, we should
evaluate these soils at that time to determine their moisture levels.
The upper 5 feet of utility trench backfill placed in pavement areas should be compacted to at
least 95 percent of the maximum dry density based on ASTM Test Method D1557. Below 5 feet
and in landscaping areas, utility trench backfill in pavement areas should be compacted to at
least 90 percent of the maximum dry density based on ASTM Test Method D1557. Pipe bedding
should consist of 5/8” crushed rock compacted to at least 90 percent of the maximum dry
density.
The contractor is responsible for removing all water-sensitive soils from the trenches regardless of
the backfill location and compaction requirements. Depending on the depth and location of
the proposed utilities, we anticipate the need to re-compact existing fill soils below the utility
structures and pipes. The contractor should use appropriate equipment and methods to avoid
damage to the utilities and/or structures during fill placement and compaction procedures.
ROCKERY WALL RECOMMENDATIONS
THUNDER HILLS CREEK
SEWER ALIGNMENT
November 1, 2016
20
8.6 GROUNDWATER INFLUENCE ON CONSTRUCTION
We do not expect groundwater to be encountered during grading or placement of the rockery
walls. If groundwater is encountered, it would likely be perched on underlying very dense
glacial till and volumes would be expected to be light.
North of Station 6+00, we would anticipate light to moderate seepage emanating from the side
slope where buttressing will be placed. Flows are expected to extend from the ground surface
down to the level of the sandstone (upper 4 to 5 feet).
Boring B-1 was located near Thunder Hills Creek and extended approximately 20 feet below the
stream level. We did not encounter groundwater in this boring, which indicates that the stream
is (at least) locally confined within the channel zones.
Groundwater seepage may be encountered in sewer trench and manhole excavations where
somewhat more permeable soils overlie dense to very dense glacial till or sandstone. We would
anticipate any seepage to migrate laterally along the weathered-unweathered till contact and
flow downward into existing sewer line backfill materials. Provided the work occurs during the
dry season (June through September), we anticipate that typical sump pumps would be suitabl e
to dewater the areas during construction.
In order to reduce the rate of downgradient groundwater flow in sewer trenches following
construction, we recommend bedding the sewer lines with 5/8” minus crushed rock. The rock
should be compacted to at least 90 percent of the modified proctor. If significant volumes of
groundwater are encountered in utility excavations, we can provide location-specific
recommendations for mitigation, if necessary. These may include lateral drainage placement to
reduce/divert groundwater toward the stream, or modifications to bedding and backfill.
8.7 ACCESS ROADWAY CONSTRUCTION
The existing access roadway is underlain by several inches of variably compacted crushed rock
(5/8” to 1-1/4” minus) which is underlain by variable density fill and native soils. We antic ipate
that the fill consists of previously excavated native soils (silty-sand with gravel). In general, the fill
likely ranges from a few inches in thickness up to a few feet; however, up to 15 feet of fill was
observed in borings in the vicinity of Stati on 7+00.
The fill and native soils have high fines content and should be considered to be very moisture
sensitive. These materials will degrade when exposed to wet weather conditions. We expect
that the upper 1 to 2 feet of existing soils may degrade during construction, primarily due to
heavy traffic loads. If this occurs, the degraded soils should be removed and replaced with
suitable structural fill placed and compacted per Section 8.1.1.
ROCKERY WALL RECOMMENDATIONS
THUNDER HILLS CREEK
SEWER ALIGNMENT
November 1, 2016
21
9.0 Construction Field Reviews
Stantec should be retained to provide part time field review during construction in order to verify
that the soil conditions encountered are consistent with our design assumptions and that the
intent of our recommendations is being met. This will require field and engineering review to:
Observe all aspects of rockery, rock buttress, and access roadway construction
Monitor temporary excavations, slope stability, and grading activities
Density testing to verify compaction of structural fills
Utility, backfill, and bedding placement
Geotechnical design services should also be anticipated during the subsequent final design
phase to support the structural design and address specific issues arising during this phase. Field
and engineering review services will also be required during the construction phase in order to
provide a Final Letter for the project.
10.0 Closure
This report was prepared for the exclusive use of the City of Renton and their appointed
consultants. Any use of this report or the material contained herein by third parties, or for other
than the intended purpose, should first be approved in writing by Stantec.
The recommendations contained in this report are based on limited data from provided test
holes, and proposed construction. We should be provided with the final plans and
specifications to verify that the intent of our recommendations has been implemented into the
design.
Use of this report is subject to the Statement of General Conditions provided in Appendix A. It is
the responsibility of the City of Renton who is identified as “the Client” within the Statement of
General Conditions, and its agents to review the conditions and to notify Stantec should any of
these not be satisfied.
ROCKERY WALL RECOMMENDATIONS
THUNDER HILLS CREEK
SEWER ALIGNMENT
November 1, 2016
22
Respectfully submitted,
Stantec Consulting Services, Inc.
Original signed by: Original signed by:
11/1/16
Phil Haberman, P.G., P.E.G. Sean Caraway, P.E.
Senior Engineering Geologist Senior Geotechnical Engineer
PH/sc
APPENDIX A
Statement of General Conditions
Statement of General Conditions
USE OF THIS REPORT: This report has been prepared for the sole benefit of the Client or its agent and may not be used by
any third party without the express written consent of Stantec Consulting Services, Inc. and the Client. Any use which a
third party makes of this report is the responsibility of such third party.
BASIS OF THE REPORT: The information, opinions, and/or recommendations made in this report are in accordance with
Stantec Consulting Services, Inc.’s present understanding of the site specific project as described by the Client. The
applicability of these is restricted to the site conditions encountered at the time of the investigation or study. If the
proposed site specific project differs or is modified from what is described in this report or if the site conditions are altered,
this report is no longer valid unless Stantec Consulting Services, Inc. is requested by the Client to review and revise the
report to reflect the differing or modified project specifics and/or the altered site conditions.
STANDARD OF CARE: Preparation of this report, and all associated work, was carried out in accordance with the normally
accepted standard of care in the state of execution for the specific professional service provided to the Client. No other
warranty is made.
INTERPRETATION OF SITE CONDITIONS: Soil, rock, or other material descriptions, and statements regarding their condition,
made in this report are based on site conditions encountered by Stantec Consulting Services, Inc. at the time of the work
and at the specific testing and/or sampling locations. Classifications and statements of condition have been made in
accordance with normally accepted practices which are judgmental in nature; no specific description should be
considered exact, but rather reflective of the anticipated material behavior. Extrapolation of in situ conditions can only
be made to some limited extent beyond the sampling or test points. The extent depends on variability of the soil, rock
and groundwater conditions as influenced by geological processes, construction activity, and site use.
VARYING OR UNEXPECTED CONDITIONS: Should any site or subsurface conditions be encountered that are different from
those described in this report or encountered at the test locations, Stantec Consulting Services, Inc. must be notified
immediately to assess if the varying or unexpected conditions are substantial and if reassessments of the report
conclusions or recommendations are required. Stantec Consulting Services, Inc. will not be responsible to any party for
damages incurred as a result of failing to notify Stantec Consulting Services, Inc. that differing site or sub-surface
conditions are present upon becoming aware of such conditions.
PLANNING, DESIGN, OR CONSTRUCTION: Development or design plans and specifications should be reviewed by Stantec
Consulting Services, Inc., sufficiently ahead of initiating the next project stage (property acquisition, tender, construction,
etc), to confirm that this report completely addresses the elaborated project specifics and that the contents of this
report have been properly interpreted. Specialty quality assurance services (field observations and testing) during
construction are a necessary part of the evaluation of sub-subsurface conditions and site preparation works. Site work
relating to the recommendations included in this report should only be carried out in the presence of a qualified
geotechnical engineer; Stantec Consulting Services, Inc. cannot be responsible for site work carried out without being
present.
APPENDIX B
10.2
APPENDIX B
Figures: Vicinity Map
Site Plans
Rockery Diagram
SITE
N
VICINITY MAP
FIGURE 1
11130 NE 33rd Place, Suite 200
Bellevue, WA 98004
(425) 869-9448
(425) 869-1190 (Fax)
www.stantec.com
Project
Location
Renton
WASHINGTON
Thunder Hills Creek
Renton, Washington
Dec., 2014 2002003607
SITE PLAN
FIGURE 2
11130 NE 33rd Place, Suite 200
Bellevue, WA 98004
(425) 869-9448
(425) 869-1190 (Fax)
www.stantec.com
Approximate Boring Location
Approximate Boring Location (P&EE)
B-1
PB-1
Thunder Hills Creek
Renton, Washington
Oct., 2016 2002003611VVN
PB-1
B-3
B-4
PB-2
B-1
PB-5
PB-3
PB-4
B-2
New Rock Buttress
New Rock Buttress
Rockery Wall No. 1
Rockery Wall No. 1 Rockery Wall No. 2
SITE PLAN
FIGURE 3
11130 NE 33rd Place, Suite 200
Bellevue, WA 98004
(425) 869-9448
(425) 869-1190 (Fax)
www.stantec.com
Approximate Hand Boring LocationHB-1 Thunder Hills Creek
Renton, Washington
Oct., 2016 2002003611VVN
HB-1
Rockery Wall No. 2
Rockery Wall No. 3
SITE PLAN
FIGURE 4
11130 NE 33rd Place, Suite 200
Bellevue, WA 98004
(425) 869-9448
(425) 869-1190 (Fax)
www.stantec.com
Thunder Hills Creek
Renton, Washington
Oct., 2016 2002003611VVN
HB-2
HB-3
Approximate Hand Boring LocationHB-1
Rockery Wall No. 4
Rockery Wall No. 5
SITE PLAN
FIGURE 5
11130 NE 33rd Place, Suite 200
Bellevue, WA 98004
(425) 869-9448
(425) 869-1190 (Fax)
www.stantec.com
Thunder Hills Creek
Renton, Washington
Oct., 2016 2002003611VVN
HB-4
HB-5
Approximate Hand Boring LocationHB-1
Rockery Wall No. 6
Possible Wall
SITE PLAN
FIGURE 6
11130 NE 33rd Place, Suite 200
Bellevue, WA 98004
(425) 869-9448
(425) 869-1190 (Fax)
www.stantec.com
Thunder Hills Creek
Renton, Washington
Oct., 2016 2002003611VVN
ROCKERY
DIAGRAM
FIGURE 7
11130 NE 33rd Place, Suite 200
Bellevue, WA 98004
(425) 869-9448
(425) 869-1190 (Fax)
www.stantec.com
1 Max.
2 Min.
Medium Dense or Firmer
Native Soils
Minimum 12”
4” Diameter Perforated
PVC Pipe
2-4” Quarry Rock
Min. 1.5’
Max. 3’
1
6
Max. 10’
Thunder Hills Sewer Interceptor
October, 2016 2002003611
APPENDIX C
Boring Logs & Design Spreadsheets
Vegetation/Topsoil
SM; Medium dense to dense, silty-sand with variable amounts of gravel
and debris, dark yellowish brown to grayish brown, moist to very moist.
(Fill)
ML; Stiff to very stiff, silt with variable amounts of sand, trace gravel,
trace debris, trace woody debris, grayish brown to olive gray, moist to
very moist. (Fill)
ML; Stiff, silt with variable amounts of sand, trace gravel, trace woody
debris, olive gray, moist. (Highly Weathered Renton Formation)
SM; Medium dense, silty-sand, tan to yellow clasts of highly weathered
sandstone, moist. (Renton Formation - Slightly Weathered)
Borehole terminated at 25 feet.
SM
ML
ML
SM
7
6
4
2
16
17
3
3
3
7
11
12
2
4
3
3
4
6
2
3
5
5
4
7
INITIAL DTW (ft):Not Encountered
WELL CASING DIA. (in):---
STARTED
B-1
EXCAVATION COMPANY:CN
EQUIPMENT:Limited Access DEPTH (ft):25.0
BORING NO.:
SAMPLING EQUIPMENT:Split Spoon CHECKED BY:GS
Time &Depth(feet)5
10
15
20
25
PROJECT NUMBER:2002003607
PROJECT:Thunder Hills Interceptor
STATIC DTW (ft):Not Encountered
LONG:LAT:COMPLETED:10/17/14 10/17/14
LOGGED BY:PH
GROUND ELEV (ft):TOC ELEV (ft):
LOCATION:Renton, WA
Description
NORTHING (ft):EASTING (ft):
PAGE 1 OF 1
USCSGraphicLogMETHOD:HSA SIZE:6
WELL DEPTH (ft):---
EXCAVATION / INSTALLATION:GEO FORM 304 THUNDER HILLS.GPJ STANTEC ENVIRO TEMPLATE 010509.GDT 2/12/15MeasuredRecov.(feet)Depth(feet)5
10
15
20
25BlowCountSampleHeadspacePID(units)Time
Sample ID
Topsoil/Vegetation
SM; Medium dense, silty-sand with variable amounts of gravel, trace
debris, yellowish brown, moist. (Fill)
SM; Dense, silty-sand with variable amounts of gravel, sandstone
remnants at 8.5-9 feet, yellowish brown to grayish brown, moist. (Glacial
Till)
Borehole terminated at 9 feet.
SM
SM
2
3
9
10
15
11
5
14
19
16
17
22
INITIAL DTW (ft):Not Encountered
WELL CASING DIA. (in):---
STARTED
B-2
EXCAVATION COMPANY:CN
EQUIPMENT:Limited Access DEPTH (ft):9.0
BORING NO.:
SAMPLING EQUIPMENT:Split Spoon CHECKED BY:GS
Time &Depth(feet)5
10
PROJECT NUMBER:2002003607
PROJECT:Thunder Hills Interceptor
STATIC DTW (ft):Not Encountered
LONG:LAT:COMPLETED:10/20/14 10/20/14
LOGGED BY:PH
GROUND ELEV (ft):TOC ELEV (ft):
LOCATION:Renton, WA
Description
NORTHING (ft):EASTING (ft):
PAGE 1 OF 1
USCSGraphicLogMETHOD:HSA SIZE:6
WELL DEPTH (ft):---
EXCAVATION / INSTALLATION:GEO FORM 304 THUNDER HILLS.GPJ STANTEC ENVIRO TEMPLATE 010509.GDT 2/12/15MeasuredRecov.(feet)Depth(feet)5
10BlowCountSampleHeadspacePID(units)Time
Sample ID
Topsoil/Vegetation
SM; Medium dense, silty-sand with variable amounts of gravel, trace
debris, yellowish brown, moist. (Fill)
SM; Dense, silty-sand with variable amounts of gravel, yellowish brown
to grayish brown, moist. (Glacial Till)
Borehole terminated at 9 feet.
SM
SM
2
3
5
10
11
10
8
14
15
18
20
22
INITIAL DTW (ft):Not Encountered
WELL CASING DIA. (in):---
STARTED
B-3
EXCAVATION COMPANY:CN
EQUIPMENT:Limited Access DEPTH (ft):9.0
BORING NO.:
SAMPLING EQUIPMENT:Split Spoon CHECKED BY:GS
Time &Depth(feet)5
10
PROJECT NUMBER:2002003607
PROJECT:Thunder Hills Interceptor
STATIC DTW (ft):Not Encountered
LONG:LAT:COMPLETED:10/20/14 10/20/14
LOGGED BY:PH
GROUND ELEV (ft):TOC ELEV (ft):
LOCATION:Renton, WA
Description
NORTHING (ft):EASTING (ft):
PAGE 1 OF 1
USCSGraphicLogMETHOD:HSA SIZE:6
WELL DEPTH (ft):---
EXCAVATION / INSTALLATION:GEO FORM 304 THUNDER HILLS.GPJ STANTEC ENVIRO TEMPLATE 010509.GDT 2/12/15MeasuredRecov.(feet)Depth(feet)5
10BlowCountSampleHeadspacePID(units)Time
Sample ID
Quarry rock
SM; Loose to medium dense, silty-sand with variable amounts of gravel,
trace debris, yellowish brown, moist to wet. (Fill)
SM; Dense to hard, slightly weathered sandstone, yellowish brown to
tan, moist. (Renton Formation)
Borehole terminated at 6 feet.
SM
SM
2
5
4
8
12
11
50
INITIAL DTW (ft):Not Encountered
WELL CASING DIA. (in):---
STARTED
B-4
EXCAVATION COMPANY:CN
EQUIPMENT:Limited Access DEPTH (ft):5.0
BORING NO.:
SAMPLING EQUIPMENT:Split Spoon CHECKED BY:GS
Time &Depth(feet)5
PROJECT NUMBER:2002003607
PROJECT:Thunder Hills Interceptor
STATIC DTW (ft):Not Encountered
LONG:LAT:COMPLETED:10/20/14 10/20/14
LOGGED BY:PH
GROUND ELEV (ft):TOC ELEV (ft):
LOCATION:Renton, WA
Description
NORTHING (ft):EASTING (ft):
PAGE 1 OF 1
USCSGraphicLogMETHOD:HSA SIZE:6
WELL DEPTH (ft):---
EXCAVATION / INSTALLATION:GEO FORM 304 THUNDER HILLS.GPJ STANTEC ENVIRO TEMPLATE 010509.GDT 2/12/15MeasuredRecov.(feet)Depth(feet)5BlowCountSampleHeadspacePID(units)Time
Sample ID
ROCKERY DESIGN
Job Name
Job No.
Designer
Date
This spreadsheet calculates:
FS Overturning 2 Typically at least 2
FS Sliding 1.8 Typically at least 1.8 (includes FS for Coefficient of Friction)
Converted to radians
Total Height (H) = 5 ft
Internal Angle of Friction of Retained Soil (phi)= 36 deg 0.63 rad
Moist Unit Weight of Retained Soil (pcf) = 120 pcf br/H 0.5
Diameter of Base Rock (br) = 2.5 ft x2 = H/batter 0.833
Diameter of Top Rock (tr) = 2 ft x3 = H+tr-br+tiny 0.333
Batter of Rockery Face (s1) = 6 V to 1H
Soil/ Wall Friction Angle (delta) = 20 deg 0.35 rad
Backslope Angle (alpha)= 22 deg 0.38 rad
Surcharge (q)= 0 psf
Internal Angle of Friction of Subgrade Soil (phi2)= 36 deg 0.63 rad
Rock Unit Weight = 155 pcf
Percent Face Rock = 70%
sin^2(beta+phi) 0.591
Back of Wall Angle from Horizontal (beta)= 93.8 deg
Back of Rockery slope (s2) = 15.0 V to 1H 1.64 rad sin^2(beta) 0.996
Active Earth Pressure Coefficient (Ka) = 0.282 sin(beta-delta) 0.960
Horiz Distance of Rockery Centroid From Toe (x)=1.54 ft SIN(phi+delta)SIN(phi-alpha)/SIN(beta-delta)SIN(beta+alpha) 0.232
Horiz Dist Between Toe and Back of Rockery at H 2.61 ft (1+root(G25))^2 2.194
Weight of Rockery (Wn)=1221 lb/ft (I21)(I22)(I24) 2.098
Horiz Component of Active Soil Load =0.960
Vert Component of Active Soil Load =0.279
Pa =423 lb/ft
Pah =406 lb/ft
Pav = 118 lb/ft
Surcharge Load on Rockery =0 lb/ft
Horiz Component of Surcharge Load on Rockery =0 lb/ft
90 deg 1.57 rad
Equivalent Fluid Pressure (ap) 34 pcf
Resisting OT Mom 1883
Factor of Safety for Overturning =2.78 OK Driving OT Mom 676
Factor of Safety for Sliding =2.39 OK Resisting Slid F 972
Driving Slid F 406
Wn = (Rock Unit Weight)(Percent Face Rock)(H)(br+tr)/2
Ka = SIN^2(beta+phi)
SIN^2(beta)SIN(beta-delta)(1+SQRT(SIN(phi+delta)SIN(phi-alpha)/SIN(beta-delta)SIN(beta+alpha))^2
ap = (Active Pressure)(Unit Weight of Soil)
Pb = (ap)(H)+(Ka)(q)
Pa = 0.5(Ka)(Weight of soil)(H^2)
Surcharge Load on Rockery = q(Ka)(H)
x = (H/2)/s+(br+tr)/4
Horiz and Vert Components of Active Soil Loads:
Horiz = cos(90+delta-beta)
Vert = absolute value of sin(90+delta-beta)
Resisting Overturning Moment = (Rockery Weight)(Horiz Dist of Centroid from Toe)+(Pav)(Horiz Dist to Back of Rockery at H/3)
Driving Overturning Moment = (Pah)(H/3)+(Horiz Component of Surcharge Load on Rockery)(H/2)
Factor of Safety Against Overturning = Resisting Moment / Driving Moment
Resisting Sliding Force = (Rockery Weight)(tan phi2)
Driving Sliding Force = Pah+(Horiz Component of Surcharge Load on Rockery)
Factor of Safety Against Sliding = Resisting Force / Driving Force
Thunder Hills
2002003611
PH/SC
10/16/2016
ROCKERY DESIGN
Job Name
Job No.
Designer
Date
This spreadsheet calculates:
FS Overturning 2 Typically at least 2
FS Sliding 1.8 Typically at least 1.8 (includes FS for Coefficient of Friction)
Converted to radians
Total Height (H) = 5 ft
Internal Angle of Friction of Retained Soil (phi)= 36 deg 0.63 rad
Moist Unit Weight of Retained Soil (pcf) = 120 pcf br/H 0.4
Diameter of Base Rock (br) = 2 ft x2 = H/batter 0.833
Diameter of Top Rock (tr) = 1.5 ft x3 = H+tr-br+tiny 0.333
Batter of Rockery Face (s1) = 6 V to 1H
Soil/ Wall Friction Angle (delta) = 20 deg 0.35 rad
Backslope Angle (alpha)= 11 deg 0.19 rad
Surcharge (q)= 0 psf
Internal Angle of Friction of Subgrade Soil (phi2)= 36 deg 0.63 rad
Rock Unit Weight = 155 pcf
Percent Face Rock = 70%
sin^2(beta+phi) 0.591
Back of Wall Angle from Horizontal (beta)= 93.8 deg
Back of Rockery slope (s2) = 15.0 V to 1H 1.64 rad sin^2(beta) 0.996
Active Earth Pressure Coefficient (Ka) = 0.237 sin(beta-delta) 0.960
Horiz Distance of Rockery Centroid From Toe (x)=1.29 ft SIN(phi+delta)SIN(phi-alpha)/SIN(beta-delta)SIN(beta+alpha) 0.377
Horiz Dist Between Toe and Back of Rockery at H 2.11 ft (1+root(G25))^2 2.605
Weight of Rockery (Wn)=949 lb/ft (I21)(I22)(I24) 2.491
Horiz Component of Active Soil Load =0.960
Vert Component of Active Soil Load =0.279
Pa =356 lb/ft
Pah =342 lb/ft
Pav = 99 lb/ft
Surcharge Load on Rockery =0 lb/ft
Horiz Component of Surcharge Load on Rockery =0 lb/ft
90 deg 1.57 rad
Equivalent Fluid Pressure (ap) 28 pcf
Resisting OT Mom 1227
Factor of Safety for Overturning =2.15 OK Driving OT Mom 570
Factor of Safety for Sliding =2.23 OK Resisting Slid F 761
Driving Slid F 342
Wn = (Rock Unit Weight)(Percent Face Rock)(H)(br+tr)/2
Ka = SIN^2(beta+phi)
SIN^2(beta)SIN(beta-delta)(1+SQRT(SIN(phi+delta)SIN(phi-alpha)/SIN(beta-delta)SIN(beta+alpha))^2
ap = (Active Pressure)(Unit Weight of Soil)
Pb = (ap)(H)+(Ka)(q)
Pa = 0.5(Ka)(Weight of soil)(H^2)
Surcharge Load on Rockery = q(Ka)(H)
x = (H/2)/s+(br+tr)/4
Horiz and Vert Components of Active Soil Loads:
Horiz = cos(90+delta-beta)
Vert = absolute value of sin(90+delta-beta)
Resisting Overturning Moment = (Rockery Weight)(Horiz Dist of Centroid from Toe)+(Pav)(Horiz Dist to Back of Rockery at H/3)
Driving Overturning Moment = (Pah)(H/3)+(Horiz Component of Surcharge Load on Rockery)(H/2)
Factor of Safety Against Overturning = Resisting Moment / Driving Moment
Resisting Sliding Force = (Rockery Weight)(tan phi2)
Driving Sliding Force = Pah+(Horiz Component of Surcharge Load on Rockery)
Factor of Safety Against Sliding = Resisting Force / Driving Force
Thunder Hills
2002003611
PH/SC
10/16/2016
ROCKERY DESIGN
Job Name
Job No.
Designer
Date
This spreadsheet calculates:
FS Overturning 2 Typically at least 2
FS Sliding 1.8 Typically at least 1.8 (includes FS for Coefficient of Friction)
Converted to radians
Total Height (H) = 6 ft
Internal Angle of Friction of Retained Soil (phi)= 36 deg 0.63 rad
Moist Unit Weight of Retained Soil (pcf) = 120 pcf br/H 0.5
Diameter of Base Rock (br) = 3 ft x2 = H/batter 1.000
Diameter of Top Rock (tr) = 2 ft x3 = H+tr-br+tiny 0.000
Batter of Rockery Face (s1) = 6 V to 1H
Soil/ Wall Friction Angle (delta) = 20 deg 0.35 rad
Backslope Angle (alpha)= 22 deg 0.38 rad
Surcharge (q)= 0 psf
Internal Angle of Friction of Subgrade Soil (phi2)= 36 deg 0.63 rad
Rock Unit Weight = 155 pcf
Percent Face Rock = 70%
sin^2(beta+phi) 0.656
Back of Wall Angle from Horizontal (beta)= 90.0 deg
Back of Rockery slope (s2) = ######## V to 1H 1.57 rad sin^2(beta) 1.000
Active Earth Pressure Coefficient (Ka) = 0.319 sin(beta-delta) 0.939
Horiz Distance of Rockery Centroid From Toe (x)=1.75 ft SIN(phi+delta)SIN(phi-alpha)/SIN(beta-delta)SIN(beta+alpha) 0.230
Horiz Dist Between Toe and Back of Rockery at H 3.00 ft (1+root(G25))^2 2.189
Weight of Rockery (Wn)=1628 lb/ft (I21)(I22)(I24) 2.057
Horiz Component of Active Soil Load =0.940
Vert Component of Active Soil Load =0.342
Pa =689 lb/ft
Pah =647 lb/ft
Pav = 235 lb/ft
Surcharge Load on Rockery =0 lb/ft
Horiz Component of Surcharge Load on Rockery =0 lb/ft
90 deg 1.57 rad
Equivalent Fluid Pressure (ap) 38 pcf
Resisting OT Mom 2849
Factor of Safety for Overturning =2.20 OK Driving OT Mom 1294
Factor of Safety for Sliding =2.09 OK Resisting Slid F 1353
Driving Slid F 647
Wn = (Rock Unit Weight)(Percent Face Rock)(H)(br+tr)/2
Ka = SIN^2(beta+phi)
SIN^2(beta)SIN(beta-delta)(1+SQRT(SIN(phi+delta)SIN(phi-alpha)/SIN(beta-delta)SIN(beta+alpha))^2
ap = (Active Pressure)(Unit Weight of Soil)
Pb = (ap)(H)+(Ka)(q)
Pa = 0.5(Ka)(Weight of soil)(H^2)
Surcharge Load on Rockery = q(Ka)(H)
x = (H/2)/s+(br+tr)/4
Horiz and Vert Components of Active Soil Loads:
Horiz = cos(90+delta-beta)
Vert = absolute value of sin(90+delta-beta)
Resisting Overturning Moment = (Rockery Weight)(Horiz Dist of Centroid from Toe)+(Pav)(Horiz Dist to Back of Rockery at H/3)
Driving Overturning Moment = (Pah)(H/3)+(Horiz Component of Surcharge Load on Rockery)(H/2)
Factor of Safety Against Overturning = Resisting Moment / Driving Moment
Resisting Sliding Force = (Rockery Weight)(tan phi2)
Driving Sliding Force = Pah+(Horiz Component of Surcharge Load on Rockery)
Factor of Safety Against Sliding = Resisting Force / Driving Force
Thunder Hills
2002003611
PH/SC
10/16/2016
ROCKERY DESIGN
Job Name
Job No.
Designer
Date
This spreadsheet calculates:
FS Overturning 2 Typically at least 2
FS Sliding 1.8 Typically at least 1.8 (includes FS for Coefficient of Friction)
Converted to radians
Total Height (H) = 6 ft
Internal Angle of Friction of Retained Soil (phi)= 36 deg 0.63 rad
Moist Unit Weight of Retained Soil (pcf) = 120 pcf br/H 0.41666667
Diameter of Base Rock (br) = 2.5 ft x2 = H/batter 1.000
Diameter of Top Rock (tr) = 2 ft x3 = H+tr-br+tiny 0.500
Batter of Rockery Face (s1) = 6 V to 1H
Soil/ Wall Friction Angle (delta) = 20 deg 0.35 rad
Backslope Angle (alpha)= 11 deg 0.19 rad
Surcharge (q)= 0 psf
Internal Angle of Friction of Subgrade Soil (phi2)= 36 deg 0.63 rad
Rock Unit Weight = 155 pcf
Percent Face Rock = 70%
sin^2(beta+phi) 0.575
Back of Wall Angle from Horizontal (beta)= 94.7 deg
Back of Rockery slope (s2) = 12.0 V to 1H 1.65 rad sin^2(beta) 0.993
Active Earth Pressure Coefficient (Ka) = 0.230 sin(beta-delta) 0.965
Horiz Distance of Rockery Centroid From Toe (x)=1.63 ft SIN(phi+delta)SIN(phi-alpha)/SIN(beta-delta)SIN(beta+alpha) 0.377
Horiz Dist Between Toe and Back of Rockery at H 2.67 ft (1+root(G25))^2 2.605
Weight of Rockery (Wn)=1465 lb/ft (I21)(I22)(I24) 2.496
Horiz Component of Active Soil Load =0.965
Vert Component of Active Soil Load =0.263
Pa =497 lb/ft
Pah =480 lb/ft
Pav = 131 lb/ft
Surcharge Load on Rockery =0 lb/ft
Horiz Component of Surcharge Load on Rockery =0 lb/ft
90 deg 1.57 rad
Equivalent Fluid Pressure (ap) 28 pcf
Resisting OT Mom 2381
Factor of Safety for Overturning =2.48 OK Driving OT Mom 960
Factor of Safety for Sliding =2.41 OK Resisting Slid F 1158
Driving Slid F 480
Wn = (Rock Unit Weight)(Percent Face Rock)(H)(br+tr)/2
Ka = SIN^2(beta+phi)
SIN^2(beta)SIN(beta-delta)(1+SQRT(SIN(phi+delta)SIN(phi-alpha)/SIN(beta-delta)SIN(beta+alpha))^2
ap = (Active Pressure)(Unit Weight of Soil)
Pb = (ap)(H)+(Ka)(q)
Pa = 0.5(Ka)(Weight of soil)(H^2)
Surcharge Load on Rockery = q(Ka)(H)
x = (H/2)/s+(br+tr)/4
Horiz and Vert Components of Active Soil Loads:
Horiz = cos(90+delta-beta)
Vert = absolute value of sin(90+delta-beta)
Resisting Overturning Moment = (Rockery Weight)(Horiz Dist of Centroid from Toe)+(Pav)(Horiz Dist to Back of Rockery at H/3)
Driving Overturning Moment = (Pah)(H/3)+(Horiz Component of Surcharge Load on Rockery)(H/2)
Factor of Safety Against Overturning = Resisting Moment / Driving Moment
Resisting Sliding Force = (Rockery Weight)(tan phi2)
Driving Sliding Force = Pah+(Horiz Component of Surcharge Load on Rockery)
Factor of Safety Against Sliding = Resisting Force / Driving Force
Thunder Hills
2002003611
PH/SC
10/16/2016
ROCKERY DESIGN
Job Name
Job No.
Designer
Date
This spreadsheet calculates:
FS Overturning 2 Typically at least 2
FS Sliding 1.8 Typically at least 1.8 (includes FS for Coefficient of Friction)
Converted to radians
Total Height (H) = 7 ft
Internal Angle of Friction of Retained Soil (phi)= 36 deg 0.63 rad
Moist Unit Weight of Retained Soil (pcf) = 120 pcf br/H 0.5
Diameter of Base Rock (br) = 3.5 ft x2 = H/batter 1.167
Diameter of Top Rock (tr) = 2.5 ft x3 = H+tr-br+tiny 0.167
Batter of Rockery Face (s1) = 6 V to 1H
Soil/ Wall Friction Angle (delta) = 20 deg 0.35 rad
Backslope Angle (alpha)= 22 deg 0.38 rad
Surcharge (q)= 0 psf
Internal Angle of Friction of Subgrade Soil (phi2)= 36 deg 0.63 rad
Rock Unit Weight = 155 pcf
Percent Face Rock = 70%
sin^2(beta+phi) 0.633
Back of Wall Angle from Horizontal (beta)= 91.3 deg
Back of Rockery slope (s2) = 42.0 V to 1H 1.59 rad sin^2(beta) 0.999
Active Earth Pressure Coefficient (Ka) = 0.305 sin(beta-delta) 0.947
Horiz Distance of Rockery Centroid From Toe (x)=2.08 ft SIN(phi+delta)SIN(phi-alpha)/SIN(beta-delta)SIN(beta+alpha) 0.230
Horiz Dist Between Toe and Back of Rockery at H 3.56 ft (1+root(G25))^2 2.190
Weight of Rockery (Wn)=2279 lb/ft (I21)(I22)(I24) 2.074
Horiz Component of Active Soil Load =0.948
Vert Component of Active Soil Load =0.319
Pa =897 lb/ft
Pah =850 lb/ft
Pav = 287 lb/ft
Surcharge Load on Rockery =0 lb/ft
Horiz Component of Surcharge Load on Rockery =0 lb/ft
90 deg 1.57 rad
Equivalent Fluid Pressure (ap) 37 pcf
Resisting OT Mom 4748
Factor of Safety for Overturning =2.39 OK Driving OT Mom 1984
Factor of Safety for Sliding =2.19 OK Resisting Slid F 1862
Driving Slid F 850
Wn = (Rock Unit Weight)(Percent Face Rock)(H)(br+tr)/2
Ka = SIN^2(beta+phi)
SIN^2(beta)SIN(beta-delta)(1+SQRT(SIN(phi+delta)SIN(phi-alpha)/SIN(beta-delta)SIN(beta+alpha))^2
ap = (Active Pressure)(Unit Weight of Soil)
Pb = (ap)(H)+(Ka)(q)
Pa = 0.5(Ka)(Weight of soil)(H^2)
Surcharge Load on Rockery = q(Ka)(H)
x = (H/2)/s+(br+tr)/4
Horiz and Vert Components of Active Soil Loads:
Horiz = cos(90+delta-beta)
Vert = absolute value of sin(90+delta-beta)
Resisting Overturning Moment = (Rockery Weight)(Horiz Dist of Centroid from Toe)+(Pav)(Horiz Dist to Back of Rockery at H/3)
Driving Overturning Moment = (Pah)(H/3)+(Horiz Component of Surcharge Load on Rockery)(H/2)
Factor of Safety Against Overturning = Resisting Moment / Driving Moment
Resisting Sliding Force = (Rockery Weight)(tan phi2)
Driving Sliding Force = Pah+(Horiz Component of Surcharge Load on Rockery)
Factor of Safety Against Sliding = Resisting Force / Driving Force
Thunder Hills
2002003611
PH/SC
10/16/2016
ROCKERY DESIGN
Job Name
Job No.
Designer
Date
This spreadsheet calculates:
FS Overturning 2 Typically at least 2
FS Sliding 1.8 Typically at least 1.8 (includes FS for Coefficient of Friction)
Converted to radians
Total Height (H) = 7 ft
Internal Angle of Friction of Retained Soil (phi)= 36 deg 0.63 rad
Moist Unit Weight of Retained Soil (pcf) = 120 pcf br/H 0.42857143
Diameter of Base Rock (br) = 3 ft x2 = H/batter 1.167
Diameter of Top Rock (tr) = 2 ft x3 = H+tr-br+tiny 0.167
Batter of Rockery Face (s1) = 6 V to 1H
Soil/ Wall Friction Angle (delta) = 20 deg 0.35 rad
Backslope Angle (alpha)= 11 deg 0.19 rad
Surcharge (q)= 0 psf
Internal Angle of Friction of Subgrade Soil (phi2)= 36 deg 0.63 rad
Rock Unit Weight = 155 pcf
Percent Face Rock = 70%
sin^2(beta+phi) 0.633
Back of Wall Angle from Horizontal (beta)= 91.3 deg
Back of Rockery slope (s2) = 42.0 V to 1H 1.59 rad sin^2(beta) 0.999
Active Earth Pressure Coefficient (Ka) = 0.256 sin(beta-delta) 0.947
Horiz Distance of Rockery Centroid From Toe (x)=1.83 ft SIN(phi+delta)SIN(phi-alpha)/SIN(beta-delta)SIN(beta+alpha) 0.378
Horiz Dist Between Toe and Back of Rockery at H 3.06 ft (1+root(G25))^2 2.608
Weight of Rockery (Wn)=1899 lb/ft (I21)(I22)(I24) 2.470
Horiz Component of Active Soil Load =0.948
Vert Component of Active Soil Load =0.319
Pa =753 lb/ft
Pah =714 lb/ft
Pav = 241 lb/ft
Surcharge Load on Rockery =0 lb/ft
Horiz Component of Surcharge Load on Rockery =0 lb/ft
90 deg 1.57 rad
Equivalent Fluid Pressure (ap) 31 pcf
Resisting OT Mom 3482
Factor of Safety for Overturning =2.09 OK Driving OT Mom 1666
Factor of Safety for Sliding =2.18 OK Resisting Slid F 1553
Driving Slid F 714
Wn = (Rock Unit Weight)(Percent Face Rock)(H)(br+tr)/2
Ka = SIN^2(beta+phi)
SIN^2(beta)SIN(beta-delta)(1+SQRT(SIN(phi+delta)SIN(phi-alpha)/SIN(beta-delta)SIN(beta+alpha))^2
ap = (Active Pressure)(Unit Weight of Soil)
Pb = (ap)(H)+(Ka)(q)
Pa = 0.5(Ka)(Weight of soil)(H^2)
Surcharge Load on Rockery = q(Ka)(H)
x = (H/2)/s+(br+tr)/4
Horiz and Vert Components of Active Soil Loads:
Horiz = cos(90+delta-beta)
Vert = absolute value of sin(90+delta-beta)
Resisting Overturning Moment = (Rockery Weight)(Horiz Dist of Centroid from Toe)+(Pav)(Horiz Dist to Back of Rockery at H/3)
Driving Overturning Moment = (Pah)(H/3)+(Horiz Component of Surcharge Load on Rockery)(H/2)
Factor of Safety Against Overturning = Resisting Moment / Driving Moment
Resisting Sliding Force = (Rockery Weight)(tan phi2)
Driving Sliding Force = Pah+(Horiz Component of Surcharge Load on Rockery)
Factor of Safety Against Sliding = Resisting Force / Driving Force
Thunder Hills
2002003611
PH/SC
10/16/2016
ROCKERY DESIGN
Job Name
Job No.
Designer
Date
This spreadsheet calculates:
FS Overturning 2 Typically at least 2
FS Sliding 1.8 Typically at least 1.8 (includes FS for Coefficient of Friction)
Converted to radians
Total Height (H) = 8 ft
Internal Angle of Friction of Retained Soil (phi)= 36 deg 0.63 rad
Moist Unit Weight of Retained Soil (pcf) = 120 pcf br/H 0.5
Diameter of Base Rock (br) = 4 ft x2 = H/batter 1.333
Diameter of Top Rock (tr) = 2.5 ft x3 = H+tr-br+tiny -0.167
Batter of Rockery Face (s1) = 6 V to 1H
Soil/ Wall Friction Angle (delta) = 20 deg 0.35 rad
Backslope Angle (alpha)= 22 deg 0.38 rad
Surcharge (q)= 0 psf
Internal Angle of Friction of Subgrade Soil (phi2)= 36 deg 0.63 rad
Rock Unit Weight = 155 pcf
Percent Face Rock = 70%
sin^2(beta+phi) 0.675
Back of Wall Angle from Horizontal (beta)= 88.8 deg
Back of Rockery slope (s2) = -48.0 V to 1H 1.55 rad sin^2(beta) 1.000
Active Earth Pressure Coefficient (Ka) = 0.331 sin(beta-delta) 0.932
Horiz Distance of Rockery Centroid From Toe (x)=2.29 ft SIN(phi+delta)SIN(phi-alpha)/SIN(beta-delta)SIN(beta+alpha) 0.230
Horiz Dist Between Toe and Back of Rockery at H 3.94 ft (1+root(G25))^2 2.189
Weight of Rockery (Wn)=2821 lb/ft (I21)(I22)(I24) 2.039
Horiz Component of Active Soil Load =0.932
Vert Component of Active Soil Load =0.361
Pa =1271 lb/ft
Pah =1185 lb/ft
Pav = 459 lb/ft
Surcharge Load on Rockery =0 lb/ft
Horiz Component of Surcharge Load on Rockery =0 lb/ft
90 deg 1.57 rad
Equivalent Fluid Pressure (ap) 40 pcf
Resisting OT Mom 6466
Factor of Safety for Overturning =2.05 OK Driving OT Mom 3161
Factor of Safety for Sliding =2.01 OK Resisting Slid F 2382
Driving Slid F 1185
Wn = (Rock Unit Weight)(Percent Face Rock)(H)(br+tr)/2
Ka = SIN^2(beta+phi)
SIN^2(beta)SIN(beta-delta)(1+SQRT(SIN(phi+delta)SIN(phi-alpha)/SIN(beta-delta)SIN(beta+alpha))^2
ap = (Active Pressure)(Unit Weight of Soil)
Pb = (ap)(H)+(Ka)(q)
Pa = 0.5(Ka)(Weight of soil)(H^2)
Surcharge Load on Rockery = q(Ka)(H)
x = (H/2)/s+(br+tr)/4
Horiz and Vert Components of Active Soil Loads:
Horiz = cos(90+delta-beta)
Vert = absolute value of sin(90+delta-beta)
Resisting Overturning Moment = (Rockery Weight)(Horiz Dist of Centroid from Toe)+(Pav)(Horiz Dist to Back of Rockery at H/3)
Driving Overturning Moment = (Pah)(H/3)+(Horiz Component of Surcharge Load on Rockery)(H/2)
Factor of Safety Against Overturning = Resisting Moment / Driving Moment
Resisting Sliding Force = (Rockery Weight)(tan phi2)
Driving Sliding Force = Pah+(Horiz Component of Surcharge Load on Rockery)
Factor of Safety Against Sliding = Resisting Force / Driving Force
Thunder Hills
2002003611
PH/SC
10/16/2016
ROCKERY DESIGN
Job Name
Job No.
Designer
Date
This spreadsheet calculates:
FS Overturning 2 Typically at least 2
FS Sliding 1.8 Typically at least 1.8 (includes FS for Coefficient of Friction)
Converted to radians
Total Height (H) = 8 ft
Internal Angle of Friction of Retained Soil (phi)= 36 deg 0.63 rad
Moist Unit Weight of Retained Soil (pcf) = 120 pcf br/H 0.4375
Diameter of Base Rock (br) = 3.5 ft x2 = H/batter 1.333
Diameter of Top Rock (tr) = 2.5 ft x3 = H+tr-br+tiny 0.333
Batter of Rockery Face (s1) = 6 V to 1H
Soil/ Wall Friction Angle (delta) = 20 deg 0.35 rad
Backslope Angle (alpha)= 11 deg 0.19 rad
Surcharge (q)= 0 psf
Internal Angle of Friction of Subgrade Soil (phi2)= 36 deg 0.63 rad
Rock Unit Weight = 155 pcf
Percent Face Rock = 70%
sin^2(beta+phi) 0.615
Back of Wall Angle from Horizontal (beta)= 92.3 deg
Back of Rockery slope (s2) = 24.0 V to 1H 1.61 rad sin^2(beta) 0.998
Active Earth Pressure Coefficient (Ka) = 0.248 sin(beta-delta) 0.953
Horiz Distance of Rockery Centroid From Toe (x)=2.17 ft SIN(phi+delta)SIN(phi-alpha)/SIN(beta-delta)SIN(beta+alpha) 0.378
Horiz Dist Between Toe and Back of Rockery at H 3.61 ft (1+root(G25))^2 2.606
Weight of Rockery (Wn)=2604 lb/ft (I21)(I22)(I24) 2.480
Horiz Component of Active Soil Load =0.953
Vert Component of Active Soil Load =0.302
Pa =953 lb/ft
Pah =909 lb/ft
Pav = 288 lb/ft
Surcharge Load on Rockery =0 lb/ft
Horiz Component of Surcharge Load on Rockery =0 lb/ft
90 deg 1.57 rad
Equivalent Fluid Pressure (ap) 30 pcf
Resisting OT Mom 5643
Factor of Safety for Overturning =2.33 OK Driving OT Mom 2423
Factor of Safety for Sliding =2.31 OK Resisting Slid F 2100
Driving Slid F 909
Wn = (Rock Unit Weight)(Percent Face Rock)(H)(br+tr)/2
Ka = SIN^2(beta+phi)
SIN^2(beta)SIN(beta-delta)(1+SQRT(SIN(phi+delta)SIN(phi-alpha)/SIN(beta-delta)SIN(beta+alpha))^2
ap = (Active Pressure)(Unit Weight of Soil)
Pb = (ap)(H)+(Ka)(q)
Pa = 0.5(Ka)(Weight of soil)(H^2)
Surcharge Load on Rockery = q(Ka)(H)
x = (H/2)/s+(br+tr)/4
Horiz and Vert Components of Active Soil Loads:
Horiz = cos(90+delta-beta)
Vert = absolute value of sin(90+delta-beta)
Resisting Overturning Moment = (Rockery Weight)(Horiz Dist of Centroid from Toe)+(Pav)(Horiz Dist to Back of Rockery at H/3)
Driving Overturning Moment = (Pah)(H/3)+(Horiz Component of Surcharge Load on Rockery)(H/2)
Factor of Safety Against Overturning = Resisting Moment / Driving Moment
Resisting Sliding Force = (Rockery Weight)(tan phi2)
Driving Sliding Force = Pah+(Horiz Component of Surcharge Load on Rockery)
Factor of Safety Against Sliding = Resisting Force / Driving Force
Thunder Hills
2002003611
PH/SC
10/16/2016
ROCKERY DESIGN
Job Name
Job No.
Designer
Date
This spreadsheet calculates:
FS Overturning 2 Typically at least 2
FS Sliding 1.8 Typically at least 1.8 (includes FS for Coefficient of Friction)
Converted to radians
Total Height (H) = 9 ft
Internal Angle of Friction of Retained Soil (phi)= 36 deg 0.63 rad
Moist Unit Weight of Retained Soil (pcf) = 120 pcf br/H 0.44444444
Diameter of Base Rock (br) = 4 ft x2 = H/batter 1.500
Diameter of Top Rock (tr) = 3 ft x3 = H+tr-br+tiny 0.500
Batter of Rockery Face (s1) = 6 V to 1H
Soil/ Wall Friction Angle (delta) = 20 deg 0.35 rad
Backslope Angle (alpha)= 22 deg 0.38 rad
Surcharge (q)= 0 psf
Internal Angle of Friction of Subgrade Soil (phi2)= 36 deg 0.63 rad
Rock Unit Weight = 155 pcf
Percent Face Rock = 70%
sin^2(beta+phi) 0.602
Back of Wall Angle from Horizontal (beta)= 93.1 deg
Back of Rockery slope (s2) = 18.0 V to 1H 1.63 rad sin^2(beta) 0.997
Active Earth Pressure Coefficient (Ka) = 0.288 sin(beta-delta) 0.957
Horiz Distance of Rockery Centroid From Toe (x)=2.50 ft SIN(phi+delta)SIN(phi-alpha)/SIN(beta-delta)SIN(beta+alpha) 0.231
Horiz Dist Between Toe and Back of Rockery at H 4.17 ft (1+root(G25))^2 2.193
Weight of Rockery (Wn)=3418 lb/ft (I21)(I22)(I24) 2.093
Horiz Component of Active Soil Load =0.957
Vert Component of Active Soil Load =0.289
Pa =1398 lb/ft
Pah =1338 lb/ft
Pav = 404 lb/ft
Surcharge Load on Rockery =0 lb/ft
Horiz Component of Surcharge Load on Rockery =0 lb/ft
90 deg 1.57 rad
Equivalent Fluid Pressure (ap) 35 pcf
Resisting OT Mom 8546
Factor of Safety for Overturning =2.13 OK Driving OT Mom 4015
Factor of Safety for Sliding =2.07 OK Resisting Slid F 2775
Driving Slid F 1338
Wn = (Rock Unit Weight)(Percent Face Rock)(H)(br+tr)/2
Ka = SIN^2(beta+phi)
SIN^2(beta)SIN(beta-delta)(1+SQRT(SIN(phi+delta)SIN(phi-alpha)/SIN(beta-delta)SIN(beta+alpha))^2
ap = (Active Pressure)(Unit Weight of Soil)
Pb = (ap)(H)+(Ka)(q)
Pa = 0.5(Ka)(Weight of soil)(H^2)
Surcharge Load on Rockery = q(Ka)(H)
x = (H/2)/s+(br+tr)/4
Horiz and Vert Components of Active Soil Loads:
Horiz = cos(90+delta-beta)
Vert = absolute value of sin(90+delta-beta)
Resisting Overturning Moment = (Rockery Weight)(Horiz Dist of Centroid from Toe)+(Pav)(Horiz Dist to Back of Rockery at H/3)
Driving Overturning Moment = (Pah)(H/3)+(Horiz Component of Surcharge Load on Rockery)(H/2)
Factor of Safety Against Overturning = Resisting Moment / Driving Moment
Resisting Sliding Force = (Rockery Weight)(tan phi2)
Driving Sliding Force = Pah+(Horiz Component of Surcharge Load on Rockery)
Factor of Safety Against Sliding = Resisting Force / Driving Force
Thunder Hills
2002003611
PH/SC
10/16/2016
ROCKERY DESIGN
Job Name
Job No.
Designer
Date
This spreadsheet calculates:
FS Overturning 2 Typically at least 2
FS Sliding 1.8 Typically at least 1.8 (includes FS for Coefficient of Friction)
Converted to radians
Total Height (H) = 9 ft
Internal Angle of Friction of Retained Soil (phi)= 36 deg 0.63 rad
Moist Unit Weight of Retained Soil (pcf) = 120 pcf br/H 0.38888889
Diameter of Base Rock (br) = 3.5 ft x2 = H/batter 1.500
Diameter of Top Rock (tr) = 3 ft x3 = H+tr-br+tiny 1.000
Batter of Rockery Face (s1) = 6 V to 1H
Soil/ Wall Friction Angle (delta) = 20 deg 0.35 rad
Backslope Angle (alpha)= 11 deg 0.19 rad
Surcharge (q)= 0 psf
Internal Angle of Friction of Subgrade Soil (phi2)= 36 deg 0.63 rad
Rock Unit Weight = 155 pcf
Percent Face Rock = 70%
sin^2(beta+phi) 0.547
Back of Wall Angle from Horizontal (beta)= 96.3 deg
Back of Rockery slope (s2) = 9.0 V to 1H 1.68 rad sin^2(beta) 0.988
Active Earth Pressure Coefficient (Ka) = 0.219 sin(beta-delta) 0.972
Horiz Distance of Rockery Centroid From Toe (x)=2.38 ft SIN(phi+delta)SIN(phi-alpha)/SIN(beta-delta)SIN(beta+alpha) 0.377
Horiz Dist Between Toe and Back of Rockery at H 3.83 ft (1+root(G25))^2 2.606
Weight of Rockery (Wn)=3174 lb/ft (I21)(I22)(I24) 2.501
Horiz Component of Active Soil Load =0.972
Vert Component of Active Soil Load =0.236
Pa =1064 lb/ft
Pah =1034 lb/ft
Pav = 251 lb/ft
Surcharge Load on Rockery =0 lb/ft
Horiz Component of Surcharge Load on Rockery =0 lb/ft
90 deg 1.57 rad
Equivalent Fluid Pressure (ap) 26 pcf
Resisting OT Mom 7538
Factor of Safety for Overturning =2.43 OK Driving OT Mom 3101
Factor of Safety for Sliding =2.41 OK Resisting Slid F 2486
Driving Slid F 1034
Wn = (Rock Unit Weight)(Percent Face Rock)(H)(br+tr)/2
Ka = SIN^2(beta+phi)
SIN^2(beta)SIN(beta-delta)(1+SQRT(SIN(phi+delta)SIN(phi-alpha)/SIN(beta-delta)SIN(beta+alpha))^2
ap = (Active Pressure)(Unit Weight of Soil)
Pb = (ap)(H)+(Ka)(q)
Pa = 0.5(Ka)(Weight of soil)(H^2)
Surcharge Load on Rockery = q(Ka)(H)
x = (H/2)/s+(br+tr)/4
Horiz and Vert Components of Active Soil Loads:
Horiz = cos(90+delta-beta)
Vert = absolute value of sin(90+delta-beta)
Resisting Overturning Moment = (Rockery Weight)(Horiz Dist of Centroid from Toe)+(Pav)(Horiz Dist to Back of Rockery at H/3)
Driving Overturning Moment = (Pah)(H/3)+(Horiz Component of Surcharge Load on Rockery)(H/2)
Factor of Safety Against Overturning = Resisting Moment / Driving Moment
Resisting Sliding Force = (Rockery Weight)(tan phi2)
Driving Sliding Force = Pah+(Horiz Component of Surcharge Load on Rockery)
Factor of Safety Against Sliding = Resisting Force / Driving Force
Thunder Hills
2002003611
PH/SC
10/16/2016
ROCKERY DESIGN
Job Name
Job No.
Designer
Date
This spreadsheet calculates:
FS Overturning 2 Typically at least 2
FS Sliding 1.8 Typically at least 1.8 (includes FS for Coefficient of Friction)
Converted to radians
Total Height (H) = 10 ft
Internal Angle of Friction of Retained Soil (phi)= 36 deg 0.63 rad
Moist Unit Weight of Retained Soil (pcf) = 120 pcf br/H 0.45
Diameter of Base Rock (br) = 4.5 ft x2 = H/batter 1.667
Diameter of Top Rock (tr) = 3.5 ft x3 = H+tr-br+tiny 0.667
Batter of Rockery Face (s1) = 6 V to 1H
Soil/ Wall Friction Angle (delta) = 20 deg 0.35 rad
Backslope Angle (alpha)= 22 deg 0.38 rad
Surcharge (q)= 0 psf
Internal Angle of Friction of Subgrade Soil (phi2)= 36 deg 0.63 rad
Rock Unit Weight = 155 pcf
Percent Face Rock = 70%
sin^2(beta+phi) 0.591
Back of Wall Angle from Horizontal (beta)= 93.8 deg
Back of Rockery slope (s2) = 15.0 V to 1H 1.64 rad sin^2(beta) 0.996
Active Earth Pressure Coefficient (Ka) = 0.282 sin(beta-delta) 0.960
Horiz Distance of Rockery Centroid From Toe (x)=2.83 ft SIN(phi+delta)SIN(phi-alpha)/SIN(beta-delta)SIN(beta+alpha) 0.232
Horiz Dist Between Toe and Back of Rockery at H 4.72 ft (1+root(G25))^2 2.194
Weight of Rockery (Wn)=4340 lb/ft (I21)(I22)(I24) 2.098
Horiz Component of Active Soil Load =0.960
Vert Component of Active Soil Load =0.279
Pa =1690 lb/ft
Pah =1624 lb/ft
Pav = 471 lb/ft
Surcharge Load on Rockery =0 lb/ft
Horiz Component of Surcharge Load on Rockery =0 lb/ft
90 deg 1.57 rad
Equivalent Fluid Pressure (ap) 34 pcf
Resisting OT Mom 12298
Factor of Safety for Overturning =2.27 OK Driving OT Mom 5412
Factor of Safety for Sliding =2.15 OK Resisting Slid F 3493
Driving Slid F 1624
Wn = (Rock Unit Weight)(Percent Face Rock)(H)(br+tr)/2
Ka = SIN^2(beta+phi)
SIN^2(beta)SIN(beta-delta)(1+SQRT(SIN(phi+delta)SIN(phi-alpha)/SIN(beta-delta)SIN(beta+alpha))^2
ap = (Active Pressure)(Unit Weight of Soil)
Pb = (ap)(H)+(Ka)(q)
Pa = 0.5(Ka)(Weight of soil)(H^2)
Surcharge Load on Rockery = q(Ka)(H)
x = (H/2)/s+(br+tr)/4
Horiz and Vert Components of Active Soil Loads:
Horiz = cos(90+delta-beta)
Vert = absolute value of sin(90+delta-beta)
Resisting Overturning Moment = (Rockery Weight)(Horiz Dist of Centroid from Toe)+(Pav)(Horiz Dist to Back of Rockery at H/3)
Driving Overturning Moment = (Pah)(H/3)+(Horiz Component of Surcharge Load on Rockery)(H/2)
Factor of Safety Against Overturning = Resisting Moment / Driving Moment
Resisting Sliding Force = (Rockery Weight)(tan phi2)
Driving Sliding Force = Pah+(Horiz Component of Surcharge Load on Rockery)
Factor of Safety Against Sliding = Resisting Force / Driving Force
Thunder Hills
2002003611
PH/SC
10/16/2016
ROCKERY DESIGN
Job Name
Job No.
Designer
Date
This spreadsheet calculates:
FS Overturning 2 Typically at least 2
FS Sliding 1.8 Typically at least 1.8 (includes FS for Coefficient of Friction)
Converted to radians
Total Height (H) = 10 ft
Internal Angle of Friction of Retained Soil (phi)= 36 deg 0.63 rad
Moist Unit Weight of Retained Soil (pcf) = 120 pcf br/H 0.4
Diameter of Base Rock (br) = 4 ft x2 = H/batter 1.667
Diameter of Top Rock (tr) = 3 ft x3 = H+tr-br+tiny 0.667
Batter of Rockery Face (s1) = 6 V to 1H
Soil/ Wall Friction Angle (delta) = 20 deg 0.35 rad
Backslope Angle (alpha)= 11 deg 0.19 rad
Surcharge (q)= 0 psf
Internal Angle of Friction of Subgrade Soil (phi2)= 36 deg 0.63 rad
Rock Unit Weight = 155 pcf
Percent Face Rock = 70%
sin^2(beta+phi) 0.591
Back of Wall Angle from Horizontal (beta)= 93.8 deg
Back of Rockery slope (s2) = 15.0 V to 1H 1.64 rad sin^2(beta) 0.996
Active Earth Pressure Coefficient (Ka) = 0.237 sin(beta-delta) 0.960
Horiz Distance of Rockery Centroid From Toe (x)=2.58 ft SIN(phi+delta)SIN(phi-alpha)/SIN(beta-delta)SIN(beta+alpha) 0.377
Horiz Dist Between Toe and Back of Rockery at H 4.22 ft (1+root(G25))^2 2.605
Weight of Rockery (Wn)=3798 lb/ft (I21)(I22)(I24) 2.491
Horiz Component of Active Soil Load =0.960
Vert Component of Active Soil Load =0.279
Pa =1424 lb/ft
Pah =1368 lb/ft
Pav = 397 lb/ft
Surcharge Load on Rockery =0 lb/ft
Horiz Component of Surcharge Load on Rockery =0 lb/ft
90 deg 1.57 rad
Equivalent Fluid Pressure (ap) 28 pcf
Resisting OT Mom 9811
Factor of Safety for Overturning =2.15 OK Driving OT Mom 4559
Factor of Safety for Sliding =2.23 OK Resisting Slid F 3045
Driving Slid F 1368
Wn = (Rock Unit Weight)(Percent Face Rock)(H)(br+tr)/2
Ka = SIN^2(beta+phi)
SIN^2(beta)SIN(beta-delta)(1+SQRT(SIN(phi+delta)SIN(phi-alpha)/SIN(beta-delta)SIN(beta+alpha))^2
ap = (Active Pressure)(Unit Weight of Soil)
Pb = (ap)(H)+(Ka)(q)
Pa = 0.5(Ka)(Weight of soil)(H^2)
Surcharge Load on Rockery = q(Ka)(H)
x = (H/2)/s+(br+tr)/4
Horiz and Vert Components of Active Soil Loads:
Horiz = cos(90+delta-beta)
Vert = absolute value of sin(90+delta-beta)
Resisting Overturning Moment = (Rockery Weight)(Horiz Dist of Centroid from Toe)+(Pav)(Horiz Dist to Back of Rockery at H/3)
Driving Overturning Moment = (Pah)(H/3)+(Horiz Component of Surcharge Load on Rockery)(H/2)
Factor of Safety Against Overturning = Resisting Moment / Driving Moment
Resisting Sliding Force = (Rockery Weight)(tan phi2)
Driving Sliding Force = Pah+(Horiz Component of Surcharge Load on Rockery)
Factor of Safety Against Sliding = Resisting Force / Driving Force
Thunder Hills
2002003611
PH/SC
10/16/2016
ROCKERY DESIGN
Job Name
Job No.
Designer
Date
This spreadsheet calculates:
FS Overturning 2 Typically at least 2
FS Sliding 1.8 Typically at least 1.8 (includes FS for Coefficient of Friction)
Converted to radians
Total Height (H) = 11 ft
Internal Angle of Friction of Retained Soil (phi)= 36 deg 0.63 rad
Moist Unit Weight of Retained Soil (pcf) = 120 pcf br/H 0.45454545
Diameter of Base Rock (br) = 5 ft x2 = H/batter 1.833
Diameter of Top Rock (tr) = 3.5 ft x3 = H+tr-br+tiny 0.333
Batter of Rockery Face (s1) = 6 V to 1H
Soil/ Wall Friction Angle (delta) = 20 deg 0.35 rad
Backslope Angle (alpha)= 22 deg 0.38 rad
Surcharge (q)= 0 psf
Internal Angle of Friction of Subgrade Soil (phi2)= 36 deg 0.63 rad
Rock Unit Weight = 155 pcf
Percent Face Rock = 70%
sin^2(beta+phi) 0.627
Back of Wall Angle from Horizontal (beta)= 91.7 deg
Back of Rockery slope (s2) = 33.0 V to 1H 1.60 rad sin^2(beta) 0.999
Active Earth Pressure Coefficient (Ka) = 0.301 sin(beta-delta) 0.949
Horiz Distance of Rockery Centroid From Toe (x)=3.04 ft SIN(phi+delta)SIN(phi-alpha)/SIN(beta-delta)SIN(beta+alpha) 0.230
Horiz Dist Between Toe and Back of Rockery at H 5.11 ft (1+root(G25))^2 2.191
Weight of Rockery (Wn)=5072 lb/ft (I21)(I22)(I24) 2.078
Horiz Component of Active Soil Load =0.950
Vert Component of Active Soil Load =0.313
Pa =2189 lb/ft
Pah =2079 lb/ft
Pav = 686 lb/ft
Surcharge Load on Rockery =0 lb/ft
Horiz Component of Surcharge Load on Rockery =0 lb/ft
90 deg 1.57 rad
Equivalent Fluid Pressure (ap) 36 pcf
Resisting OT Mom 15430
Factor of Safety for Overturning =2.02 OK Driving OT Mom 7622
Factor of Safety for Sliding =2.01 OK Resisting Slid F 4181
Driving Slid F 2079
Wn = (Rock Unit Weight)(Percent Face Rock)(H)(br+tr)/2
Ka = SIN^2(beta+phi)
SIN^2(beta)SIN(beta-delta)(1+SQRT(SIN(phi+delta)SIN(phi-alpha)/SIN(beta-delta)SIN(beta+alpha))^2
ap = (Active Pressure)(Unit Weight of Soil)
Pb = (ap)(H)+(Ka)(q)
Pa = 0.5(Ka)(Weight of soil)(H^2)
Surcharge Load on Rockery = q(Ka)(H)
x = (H/2)/s+(br+tr)/4
Horiz and Vert Components of Active Soil Loads:
Horiz = cos(90+delta-beta)
Vert = absolute value of sin(90+delta-beta)
Resisting Overturning Moment = (Rockery Weight)(Horiz Dist of Centroid from Toe)+(Pav)(Horiz Dist to Back of Rockery at H/3)
Driving Overturning Moment = (Pah)(H/3)+(Horiz Component of Surcharge Load on Rockery)(H/2)
Factor of Safety Against Overturning = Resisting Moment / Driving Moment
Resisting Sliding Force = (Rockery Weight)(tan phi2)
Driving Sliding Force = Pah+(Horiz Component of Surcharge Load on Rockery)
Factor of Safety Against Sliding = Resisting Force / Driving Force
Thunder Hills
2002003611
PH/SC
10/16/2016
ROCKERY DESIGN
Job Name
Job No.
Designer
Date
This spreadsheet calculates:
FS Overturning 2 Typically at least 2
FS Sliding 1.8 Typically at least 1.8 (includes FS for Coefficient of Friction)
Converted to radians
Total Height (H) = 11 ft
Internal Angle of Friction of Retained Soil (phi)= 36 deg 0.63 rad
Moist Unit Weight of Retained Soil (pcf) = 120 pcf br/H 0.36363636
Diameter of Base Rock (br) = 4 ft x2 = H/batter 1.833
Diameter of Top Rock (tr) = 3.5 ft x3 = H+tr-br+tiny 1.333
Batter of Rockery Face (s1) = 6 V to 1H
Soil/ Wall Friction Angle (delta) = 20 deg 0.35 rad
Backslope Angle (alpha)= 11 deg 0.19 rad
Surcharge (q)= 0 psf
Internal Angle of Friction of Subgrade Soil (phi2)= 36 deg 0.63 rad
Rock Unit Weight = 155 pcf
Percent Face Rock = 70%
sin^2(beta+phi) 0.538
Back of Wall Angle from Horizontal (beta)= 96.9 deg
Back of Rockery slope (s2) = 8.2 V to 1H 1.69 rad sin^2(beta) 0.986
Active Earth Pressure Coefficient (Ka) = 0.215 sin(beta-delta) 0.974
Horiz Distance of Rockery Centroid From Toe (x)=2.79 ft SIN(phi+delta)SIN(phi-alpha)/SIN(beta-delta)SIN(beta+alpha) 0.378
Horiz Dist Between Toe and Back of Rockery at H 4.44 ft (1+root(G25))^2 2.607
Weight of Rockery (Wn)=4476 lb/ft (I21)(I22)(I24) 2.502
Horiz Component of Active Soil Load =0.974
Vert Component of Active Soil Load =0.226
Pa =1560 lb/ft
Pah =1519 lb/ft
Pav = 353 lb/ft
Surcharge Load on Rockery =0 lb/ft
Horiz Component of Surcharge Load on Rockery =0 lb/ft
90 deg 1.57 rad
Equivalent Fluid Pressure (ap) 26 pcf
Resisting OT Mom 12495
Factor of Safety for Overturning =2.24 OK Driving OT Mom 5570
Factor of Safety for Sliding =2.31 OK Resisting Slid F 3506
Driving Slid F 1519
Wn = (Rock Unit Weight)(Percent Face Rock)(H)(br+tr)/2
Ka = SIN^2(beta+phi)
SIN^2(beta)SIN(beta-delta)(1+SQRT(SIN(phi+delta)SIN(phi-alpha)/SIN(beta-delta)SIN(beta+alpha))^2
ap = (Active Pressure)(Unit Weight of Soil)
Pb = (ap)(H)+(Ka)(q)
Pa = 0.5(Ka)(Weight of soil)(H^2)
Surcharge Load on Rockery = q(Ka)(H)
x = (H/2)/s+(br+tr)/4
Horiz and Vert Components of Active Soil Loads:
Horiz = cos(90+delta-beta)
Vert = absolute value of sin(90+delta-beta)
Resisting Overturning Moment = (Rockery Weight)(Horiz Dist of Centroid from Toe)+(Pav)(Horiz Dist to Back of Rockery at H/3)
Driving Overturning Moment = (Pah)(H/3)+(Horiz Component of Surcharge Load on Rockery)(H/2)
Factor of Safety Against Overturning = Resisting Moment / Driving Moment
Resisting Sliding Force = (Rockery Weight)(tan phi2)
Driving Sliding Force = Pah+(Horiz Component of Surcharge Load on Rockery)
Factor of Safety Against Sliding = Resisting Force / Driving Force
Thunder Hills
2002003611
PH/SC
10/16/2016