GEOTECHNICAL INVESTIGATION
I-15 MILE POST CL 120 INTERCHANGE
MESQUITE, NEVADA
PREPARED FOR:
HORROCKS ENGINEERS2162 WEST GROVE PARKWAY, SUITE 400
PLEASANT GROVE, UTAH 84062
ATTENTION: BRIAN ATKINSON, [email protected]
PROJECT NO. 2100948 MAY 19, 2011 (Revised June 22, 2011)
TABLE OF CONTENTS
EXECUTIVE SUMMARY . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Page 1
SCOPE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Page 3
SITE CONDITIONS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Page 5
FIELD STUDY . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Page 5
SUBSURFACE CONDITIONS AND LABORATORY TESTING . . . . . . . . . . . . . . . . . Page 5
SUBSURFACE WATER . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Page 10
PROPOSED CONSTRUCTION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Page 11
RECOMMENDATIONS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Page 12A. Site Grading . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Page 12B. Permanent Shallow Foundations . . . . . . . . . . . . . . . . . . . . . . . . . Page 24C. Temporary Pile Foundations . . . . . . . . . . . . . . . . . . . . . . . . . . . . Page 27D. Concrete Slab-on-Grade/Curb . . . . . . . . . . . . . . . . . . . . . . . . . . . Page 31E. Lateral Earth Pressures . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Page 31F. Seismicity . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Page 33G. Liquefaction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Page 34H. Water Soluble Sulfates and Cement Type . . . . . . . . . . . . . . . . . . Page 35I. Corrosion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Page 35J. Construction Testing and Observation . . . . . . . . . . . . . . . . . . . . . page 36
LIMITATIONS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Page 37
FIGURES
Vicinity Map Figure 1Site Plan Figure 2Logs of Test Pits Figure 3Logs of Exploratory Borings Figures 4-9Legend and Notes of Test Pits and Exploratory Borings Figure 10Consolidation Test Results Figures 11-23Direct Shear Test Results Figures 24-29Gradation and Moisture-Density Relationship Results Figures 30-35Sieve Analysis Test Report Figures 36-45Factored Bearing Resistance vs Effective Footing Width Figure 46Driven H-Pile Capacities Figure 47Pile Head Deflection Figure 48Maximum Moment Figure 49Pile Deflection Figures 50-53
Summary of Laboratory Test Results Table 1Summary of Chemical Laboratory Test Results Table 2Subcontracted Laboratory Tests Appendix
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EXECUTIVE SUMMARY
1. The subsurface soil profile observed in the test pits excavated and the borings drilledat the site generally consists of varying thicknesses of site grading fill overlying naturalpoorly graded sand with silt to silty sand. The fill thickness observed varies fromapproximately 1 foot to approximately 31 feet. Fill was not encountered in Test Pit TP-4 and Borings B-10 through B-13 on the eastern portion of the site. Poorly gradedgravel with sand was encountered near the surface in Borings B-11 through B-13. Fatclay was encountered near the bottom of B-13 at a depth of approximately 27 feet anda layer of lean clay was encountered in Test Pit TP-2 at a depth of approximately 10feet.
2. Subsurface water was not encountered in the borings and test pits by AGEC to themaximum depth investigation, approximately 70 feet with the exception of boring B-12. Groundwater was encountered at approximately 37 feet in Boring B-12 at the timeof the exploration. This corresponds to an elevation of approximately 1,558½ feet.Review of the “Baseline Geotechnical Investigation” indicates groundwater wasencountered at depths ranging from approximately 67 to 75 feet below the existinggrade. This corresponds to an elevation ranging from approximately 1,557½ feet to1,561 feet. Fluctuations in groundwater level may occur over time. We anticipate thegroundwater depth/elevation will likely remain relatively constant throughout the year.
3. The subject site is suitable to support the proposed construction providedrecommendations included within this report are followed.
4. Observations, penetration values (blow counts) and laboratory testing indicates the fillobserved is generally moderately to well compacted and consists of silty sand to poorlygraded sand with varied amounts of gravel mixed with some clay.
5. The proposed bridge overpass may be permanently supported on conventional spreadfootings bearing on a properly compacted subgrade as provided in the PermanentShallow Foundations section of the report. Factored bearing resistances are providedon Figure 46.
6. Observations and laboratory testing indicate the on-site fill soils and natural sand soils(including soils sampled by NDOT during preparation of the Baseline GeotechnicalInvestigation), are suitable for use as Borrow, Selected Borrow and Backfill inaccordance with Sections 203 and 207 of the State of Nevada DOT, “StandardSpecifications for Road and Bridge Construction”, 2001 and “Pull Sheets” from thecontract documents. Chemical tests conducted by NDOT and by AGEC should bereferred to if corrosion to buried structures is a concern.
7. Geotechnical information related to foundations, subgrade preparation, excavation,compaction and materials, retaining structures and seismic design criteria are includedwithin this report.
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8. Information presented in this summary should not be used independent of thatcontained within the body of the report.
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SCOPE
This report presents the results of a geotechnical investigation for the proposed I-15 Mile Post
CL120 Interchange in Mesquite, Nevada at the approximate location shown on Figure 1. This
report presents the subsurface conditions encountered, laboratory test results, and
recommendations for the geotechnical aspects of the project. Geotechnical aspects include
temporary and permanent bridge foundation support recommendations, material
suitability/grading recommendations, retaining design parameters and seismic characteristics
of the subsurface soils.
Field exploration was conducted to obtain information on the subsurface conditions. Samples
obtained from the field investigation were tested in the laboratory to determine physical and
engineering characteristics of the on-site soil. Information obtained from the field and
laboratory along with information contained in the Baseline Geotechnical Investigation was
used to define conditions at the site for our engineering analysis and to develop
recommendations for the proposed construction.
This report has been prepared to summarize the data obtained during the study and to present
our conclusions and recommendations based on the proposed construction and the subsurface
conditions encountered. Design parameters and a discussion of geotechnical engineering
considerations related to construction are included in the report.
The geotechnical design criteria and recommendations are based upon the following
supporting documents and information:
1. “Geotechnical Policies and Procedures Manual”, 2005, Nevada DOT.
2. “Baseline Geotechnical Report , I-15 Milepost CL120 Interchange, Design
Build”, July, 2010, prepared by Nevada DOT, Material Division.
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3. Subsurface investigation and laboratory testing completed by AGEC.
4. “AASHTO LRFD Bridge Design Specifications”, Fifth Edition, 2010.
5. “Guide Design Specification for Bridge Temporary Works”, published by
AASHTO, 1995.
6. “Standard Specifications for Road and Bridge Construction”, State of Nevada
DOT, 2001.
7. “West Mesquite Interchange Design-Build Project”, Part 9 - Contract Documents
Appendix A Pull Sheets, April 4, 2011.
8. Drawings and plans, prepared by Horrocks Engineers.
9. “Structures Manual”, Nevada DOT, September, 2008.
10. “Manual for Design & Construction Monitoring of Soil Nail Walls”, Publication
No. FHWA-SA-96-069R, October 1998.
11. “Geotechnical Circular No. 7", Report No. FHWA0-IF-03-017, prepared for
FHWA, March 2003.
12. “Foundation Analysis and Design”, Fourth Edition, Joseph E. Bowles.
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SITE CONDITIONS
The subject site is located in Mesquite, Clark County, Nevada at the I-15 mile post CL120
interchange as shown on Figure 1. There is currently an existing 3 span bridge super
structure. We understand the existing bridge is supported on conventional spread footings.
The existing bridge facilitates the travel of the north and south bound I-15 traffic over Falcon
Ridge Parkway. Falcon Ridge Parkway is aligned beneath the overpass extending east and
intersects Mesquite Blvd. There is cultivated, undeveloped property and residences to the east
and developed commercial portions of Mesquite to the east and west.
FIELD STUDY
On March 14, 15, 16 and 17, an engineer from AGEC visited the site and observed the
excavation of 5 test pits and the drilling of 13 borings at the approximate locations shown on
the site plan, Figure 2. The test pits were excavated using a rubber tired backhoe. Borings
were drilled utilizing a truck mounted drill rig equipped with 8-inch diameter hollow-stem
augers. The test pits and borings were logged and soil samples obtained by an engineer from
AGEC. Logs of the subsurface conditions encountered in the test pits and borings are shown
graphically on Figures 3-9 with the Legend and Notes of Test Pits and Borings shown on
Figure 10.
SUBSURFACE CONDITIONS AND LABORATORY TESTING
The subsurface soil profile observed in the test pits excavated and the borings drilled at the
site generally consists of varying thicknesses of site grading fill overlying natural poorly graded
sand with silt to silty sand. The fill thickness observed varies from approximately 1 foot to
approximately 31 feet. Fill was not encountered in Test Pit TP-4 and Borings B-10 through
B-13 on the eastern portion of the site. Poorly graded gravel with sand was encountered near
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the surface in Borings B-11 through B-13. Fat clay was encountered near the bottom of B-13
at a depth of approximately 27 feet and a layer of lean clay was encountered in Test Pit TP-2
at a depth of approximately 10 feet. Asphaltic concrete pavement overlying base course was
encountered at the surface in Boring B-6.
Descriptions of the subsurface soils and encountered in the test pits and borings follows:
Asphalt - Moderate condition and black in color.
Base Course - Appears well compacted, moist and brown in color.
Cultivated soil - The cultivated soil consists of silty to clayey sand. It is loose to
medium dense, moist, contains roots and is brown in color.
Fill - (USC Soil Classification: SM to SC, AASHTO Soil Classification: A-2-4) - The fill
consists of silty sand to poorly graded sand mixed with varied amounts of gravel and
clay. It generally appears moderately to well compacted, moist, non to low plastic and
light brown in color.
Laboratory tests conducted on samples of the fill indicate in-place moisture contents
ranging from 3 to 12 percent, in-place dry densities ranging from 103 to 113 pounds
per cubic foot (pcf), gravel contents (percent retained on the No. 4 sieve) ranging from
0 to 28 percent and fines contents (percent passing the No. 200 sieve) ranging from
9 to 25 percent. Atterberg Limits tests conducted on samples of the fill indicate the
material tests is non-plastic. Moisture-density Relationship (modified proctor) tests
conducted on samples of the fill indicate maximum dry densities ranging from 122.5
to 134.5 pcf with optimum moisture contents ranging from 6.5 to 11.0 percent. R-
value tests conducted on samples of the fill indicate R-values ranging from 64 to 75
at 300 psi exudation pressure.
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Direct shear tests conducted on samples of the fill remolded at approximately 95
percent of the maximum dry density and near the optimum moisture content indicate
peak friction angles ranging from 40 to 42 degrees and peak cohesion values ranging
from 340 to 550 pounds per square foot (psf). A direct shear test conducted on a
sample of the fill in its existing condition indicates a peak friction angle of 32 degrees
and peak cohesion value 780 psf.
Several water soluble sulfate tests conducted on samples of the fill indicate water
soluble sulfate concentrations ranging from 300 to 1,200 parts per million (ppm).
Laboratory resistivity tests conducted on the fill indicate resistivities ranging from 450
to 1,400 ohm-cm. Chloride concentrations ranging from 11 to 161 ppm and pH values
ranging from 8.1 to 9.0 were also measured on samples of the fill.
A one-dimensional consolidation test conducted on a sample of the fill indicates it is
slightly moisture sensitive (collapsible) when wetted under a constant pressure of
approximately 1,000 psf and slightly compressible under additional loading. We
anticipate a portion of the measured collapse in the boring drive sample is related to
disturbance during the sampling process.
Sandy lean clay to fat clay - (USC Soil Classification: CL to CH, AASHTO Soil
Classification: A-4 to A-7-5) - The clay is medium stiff to very stiff, moist, low to high
plastic and brown in color.
Laboratory tests conducted on samples of the clay indicate in-place moisture contents
ranging from 12 to 21 percent, in-place dry densities ranging from 99 to 111 pcf and
fines contents ranging from 51 to 69 percent. Atterberg Limits tests conducted on a
samples of the clay indicate liquid limits ranging from 22 to 58 percent and a plasticity
indices ranging from of 7 to 39 percent.
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A one-dimensional consolidation test conducted on a sample of the clay (at a depth of
29 feet) indicates it is non moisture sensitive when wetted under a constant pressure
of approximately 2,000 psf and slightly compressible under additional loading.
Silty sand - (USC Soil Classification: SM, Soil Classification: AASHTO A-2-4) - The silty
sand is dense to very dense, moist, fine-grained and light brown in color.
Laboratory tests conducted on samples of the silty sand indicate in-place moisture
contents ranging from 3 to 10 percent, in-place dry densities ranging from 97 to 117
pcf, a gravel content of 2 percent and fines contents ranging from 13 to 28 percent.
A direct shear test conducted on a sample of the silty sand in its existing condition
indicates a peak friction angle of 33 degrees and peak cohesion value 350 psf.
Several one-dimensional consolidation tests conducted on samples of the silty sand
indicate the material is non to slightly moisture sensitive (collapsible) when wetted
under constant pressures of approximately 1,000 and 2,000 psf and slightly
compressible under additional loading with the exception of the near surface soil in test
pit TP-5. The consolidation tests indicate the near surface soils tested are moderately
collapsible when wetted under a constant pressure of 500 psf. We anticipate a portion
of the measured collapse in the boring drive samples is related to disturbance during
the sampling process.
Poorly graded sand with silt - (USC Soil Classification: SP-SM, AASHTO Soil
Classification: A-2-4 to A-3 to A-1-b) - The poorly graded sand with silt contains
interbedded silty sand layers and occasional gravel. It is loose to very dense, moist to
slightly moist, fine-grained, and light brown in color.
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Laboratory tests conducted on samples of the poorly graded sand with silt indicate in-
place moisture contents ranging 1 to 8 from percent, in-place dry densities ranging
from 101 to 126 pcf, a gravel content ranging from 0 to 19 percent and fines contents
ranging from 5 to 12 percent.
Several one-dimensional consolidation tests conducted on samples of the poorly graded
sand with silt indicate it is non to slightly moisture sensitive (collapsible) when wetted
under constant pressures of approximately 1,000, 2,000 and 4,000 psf and slightly
compressible under additional loading with the exception of the near surface soil in test
pit TP-5 and Boring B-4. The consolidation tests indicate these near surface soils (in
the area of TP-5 and B-4) tested are moderately collapsible when wetted under a
constant pressure of 500 psf. We anticipate a portion of the measured collapse in the
boring drive samples is related to disturbance during the sampling process.
Poorly graded gravel with sand - (USC Soil Classification: GP, AASHTO Soil
Classification: A-1-a to A-1-b) - The poorly graded gravel with sand contains occasional
cobbles. It is medium dense to very dense, moist, sub-rounded gravel and brown in
color.
Laboratory tests conducted on samples of the poorly graded gravel with sand indicate
in-place moisture contents ranging from 2 to 3 percent, gravel contents ranging from
60 to 71 percent and fines contents ranging from 2 to 4 percent.
Logs of the subsurface conditions encountered in the test pits and borings are shown
graphically on Figures 3-9 with the Legend and Notes of Test Pits and Borings shown on
Figure 10. Results of the laboratory tests are also shown on Figures 3-9 and are summarized
on the Summary of Laboratory Test Results, Table 1 and the Summary of Chemical Test
Results, Table 2. One-dimensional consolidation test results are shown graphically on Figures
11-23. Direct shear test results are shown on Figures 24-29. Moisture-Density Relationship
(Proctor) and Gradation/Soil Classification Test Results are shown on Figures 30-35.
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Gradation Test Results are shown on Figures 36-45. R-value and chemical test results
subcontracted to outside laboratories are included in the Appendix of this report.
Laboratory test results were conducted in accordance with the following Test methods:
1. Atterberg Limits: AASHTO T89 and T90.
2. Gradation (Percent passing the No. 200 sieve): AASHTO T11.
3. Gradation (All sieves): AASHTO T27.
4. Soil Class: AASHTO M145.
5. One Dimensional Consolidation: AASHTO T216.
6. Moisture Density Relationship Test (Modified Proctor): AASHTO T180.
7. Direct Shear: AASHTO T236.
8. Chlorides: AASHTO T291.
9. Resistivity: AASHTO T288.
10. Water Soluble Sulfates: AASHTO T290 and SM4500E.
11. R-Value: AASHTO T190.
12. pH: AASHTO T289.
13. Moisture of Soils: AASHTO T265.
SUBSURFACE WATER
Subsurface water was not encountered in the borings and test pits by AGEC to the maximum
depth investigation, approximately 70 feet with the exception of boring B-12. Groundwater
was encountered at approximately 37 feet in Boring B-12 at the time of the exploration. This
corresponds to an elevation of approximately 1,558½ feet. Review of the “Baseline
Geotechnical Investigation” indicates groundwater was encountered at depths ranging from
approximately 67 to 75 feet below the existing grade. This corresponds to an elevation
ranging from approximately 1,557½ feet to 1,561 feet. Fluctuations in groundwater level
may occur over time. We anticipate the groundwater depth/elevation will likely remain
relatively constant throughout the year.
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PROPOSED CONSTRUCTION
We understand it is proposed to construct new, single span bridges at the I-15 mile post CL
120 interchange. The new, single span bridge (overpass) structures will be constructed
adjacent to the existing bridges (on either side, extending over Falcon Ridge Parkway) and will
be temporarily supported on driven pile foundations. The permanent bridge foundations are
proposed to consist of conventional spread footings and will be constructed concurrently to
support the new single span bridge structures in their permanent locations. The single span
bridges will allow for widening of the underpass and Falcon Ridge Parkway.
In order to construct the permanent foundations, the slope beneath the existing bridges will
require cutting on the order of 17 to 19 feet high to provide a location for the new
foundations. In order to safely support the proposed cut, we understand it is proposed to
construct a “staged”, temporary soil nailed wall with a reinforced or shot-crete facing on both
the north and south bridge abutments. The soil nailed wall will also extend to the east and
west to support permanent cuts on either side of Falcon Ridge Parkway.
It is our understanding that upon completion of the temporary soil nailing and the permanent
bridge foundations, the bridge structures will be moved onto and permanently attached to the
new foundations after removal of the existing bridge structures. The foundation walls will
subsequently be backfilled. The new bridge placement is planned to utilize a “Fast Track”
procedure to allow the process to be completed quickly and reduce road closure requirements.
In addition, we understand it is proposed to slightly re-align the existing on and off-ramps as
well as construct roundabouts on the east and west ends of Falcon Ridge Parkway. The
roundabouts will tie into the on-ramps, off-ramps, Falcon Ridge Parkway and Mesquite Blvd.
as shown on Figure 2. In addition, it is proposed to extend Falcon Ridge Parkway south to
Leavitt Lane. This will require fill depths of up to approximately 14 feet to fill eastern portion
of the eastern roundabout and the beginning of the roadway extension. The fill depths are
planned to taper down to near the existing grade at Leavitt Lane. The side slopes of the
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extensions will be graded at 4:1 (Horizontal:Vertical).
The following loading conditions and construction criteria have been provided by Horrocks
Engineers to facilitate our engineering analysis:
1. Temporary foundations will consist of HP 14X89 or HP 14X117 H-piles.
2. Unfactored axial load on the temporary pile foundations = 205 kips per pile.
3. Unfactored axial load on temporary support piles = 70 kips.
4. Unfactored lateral load on the temporary foundations = 12 kips per pile.
5. Strength 1 loading applied to the permanent foundations = 87.4 kips/foot.
6. Service 1 loading applied to the permanent foundations = 66.0 kips/foot.
7. Estimated preliminary foundation footing size = 12 feet wide by 70 feet long.
If the proposed construction or building loads are significantly different from what are
described above, we should be notified so that we can reevaluate the recommendations given.
RECOMMENDATIONS
Based on the subsurface conditions encountered, the referenced Baseline Geotechnical
Investigation, laboratory test results and the proposed construction, the following
recommendations are provided.
A. Site Grading
Based on a description of proposed grading and the preliminary cut/fill map provided
by Horrocks, the following table provides a brief description of the proposed grading:
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Location Description of proposed grading
Permanent bridge foundation Requires cuts on the order of 17 to 19 feet
West roundabout and Underpass - Falcon Ridge
Parkway
Constructed near the existing grade with significant
cuts on either side.
Falcon Ridge Parkway and east of east
roundabout
Requires up to 14 feet of fill tapering to near the
existing grade at Leavitt Lane
East end of east roundabout Requires up to 14 feet of fill
North bound off ramp Will be cut below the existing grade
South bound on and off ramps and north bound
on ramp
Shallow fill or constructed near the existing grade
Bridge approaches Near the existing grade
1. Subgrade Preparation
a. Grubbing: Portions of the proposed alignment contain near surface
vegetation or cultivated soil, particularly along the portions of the on/off
ramps and along the alignment of the east end of Falcon Ridge Parkway.
Prior to placing site grading fill to support roadways, the existing
organics and soil containing roots and organics should be removed. We
anticipate the thickness may vary from approximately 2 to 6 inches in
areas where vegetation is observed. Clearing and grubbing should
follow the requirements of Section 201 of the NDOT Standard
Specifications for Road and Bridge Construction.
b. General: Prior to placing fill, the existing asphalt should be removed the
full depth. Consideration may be given to roto-milling the pavement
section to the full depth and re-using the material for the embankment
fill beneath Falcon Ridge Parkway or as base course beneath roadways,
if acceptable. Use of cold millings as a base layer (in the bottom half)
should be in accordance with the “Pull Sheet” for Section 302 of the
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NDOT Standard Specifications for Road and Bridge Construction. Cold
millings used as embankment fill should meet the requirements of
Section 203 of the NDOT Standard Specifications for Road and Bridge
Construction.
Subsequent to grubbing and asphalt/base removal, undiscovered loose
soils or disturbed soils should also be removed. Prior to placing fill,
base course or concrete, the exposed subgrade should be scarified at
least 8 inches, moisture conditioned and compacted to at least 90
percent of the maximum dry density as determined by Test Method No.
Nev. T101.
c. Dry/Collapsible soil removal: AGEC’s laboratory testing and observations
indicate the near surface soil in the area just east of the cultivated field
(area not currently cultivated) is loose and/or moderately collapsible
when wetted (Test Pit TP-5). The zone appears to extend to
approximately 4 feet below the existing grade. We estimate that on the
order of c inch of post construction settlement (of the roadway) may
occur for each foot of the underlying collapsible soil which is wetted
after construction.
To reduce the potential post construction settlement (resulting from
collapse), we recommend the exposed subgrade be overexcavated (in
this area) to remove the natural soils at least 2 feet below the existing
grade. In addition, the near surface soils along the east edge of
Mesquite Blvd (Boring B-10) were also observed to be loose. We
recommend this area be overexcavated to remove the natural soils at
least 1 foot below the existing grade. The approximate locations which
require additional overexcavation are shown on Figure 2. The
overexcavation should extend at least 2 feet beyond the limits of edge
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of roadway or the embankment.
Subsequent to overexcavation (one or 2 feet) and prior to placing fill or
base course, the exposed subgrade should be scarified 8 inches,
moisture conditioned and compacted to at 90 percent of the maximum
dry density as determined by Test Method No. Nev. T101. The removed
soil may be replaced in properly compacted lifts.
2. Excavation
We anticipate excavation of the on-site soils can be accomplished with typical
excavation equipment. Excavations of temporary cut slopes should be sloped
in accordance with OSHA Soil Site Class C. This will require the slopes to be
graded at a maximum slope of approximately 1½:1 (horizontal to vertical). As
an alternative, the slopes may be reinforced, shored or retained. We understand
the cut slopes along the north and south sides of Falcon Ridge Parkway
(beneath the bridge) are proposed to be reinforced with a soil nails and a
reinforced facing or shot-crete. The following section provides details which
should be considered for the soil nailed wall design and construction. We
understand the final soil nailed wall design will be provided by others.
3. Soil Nailed Walls
During and after construction, a soil nailed wall and the soil behind it tend to
deform outwards. The deformation has two components: (1) During excavation
and (2) after the soil nails are constructed due to mobilization of the soil to
achieve capacity (interaction between the soil and nail).
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We understand this movement will not be critical in the permanent soil nailed
wall locations where the wall is not supporting the existing bridge spread
footing. Controlling the anticipated movement will be necessary where the
temporary soil nailed wall is constructed adjacent and beneath the existing
bridge footings.
Due to the critical nature of the temporary soil nailed wall and facing system,
it is recommended that the proposed design include construction techniques
and analysis to control movement at the face and subsequent settlement of the
adjacent bridge foundation to allow the bridge to remain in service.
The following options may be considered to reduce potential movement of the
foundation due to lateral movement/bending of the soil nailed wall:
a. The soil nails may be drilled, partially grouted along their length and pre-
tensioned to mobilize some of the nail strength while reducing the soil
mass deformation near the wall face.
b. The spacing of the soil nails may be decreased to reduce the stresses
developed on each nail to reduce mobilization of the soil.
c. The length of the soil nails may be increased to reduce the stresses
developed on each nail which will likely reduce mobilization of the soil.
d. The soil nailed wall facing may be designed and constructed to provide
increased stiffness to assist in reducing movement at the face.
e. The face may be battered.
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Additional recommendations which should be considered for design and
construction of the soil nailed walls are provided below:
a. Preliminary analysis by AGEC indicates additional nail length may be
necessary for the temporary soil nailed walls to increase factors of
safety against failure due to potential deep seated failure resulting from
the underlying looser sand.
b. The construction of the soil nailed walls should incorporate staged
construction methods. This method will be particularly critical adjacent
to the existing bridge footings. We recommend the first cut be
conducted only to allow for installation of the first row of soil nails
beneath the existing spread footings. This may be accomplished by
cutting “notches” for each nail to assist in minimizing movement/caving
until the first row of nails are complete and have achieved strength.
Prior to cutting for the second row, the reinforced wall facing should be
constructed over the first row and allowed to achieve strength. This
process may require alternating between the north and the south
abutment.
c. The soil nailed walls should be designed in accordance with the
referenced FHWA guidelines. Loading combinations (Including dead
load, live load and earth quake) and acceptable factors of safety should
be implemented in the design as provided by FHWA.
d. The soil nailed wall design should consider internal stability, external
stability and global stability in the analysis during various stages of the
construction.
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APPLIED GEOTECHNICAL ENGINEERING CONSULTANTS, INC. 2100948
e. Corrosion of the permanent soil nailed wall should also be assessed. A
Summary of Chemical Laboratory Test Results is attached.
f. We understand the NDOT has expressed concern regarding drainage
behind the soil nailed wall face. We understand a geo-composite drain
will be placed behind the facing and will be specified in the final soil nail
design.
g. Based on observations by AGEC during our field investigation, we
anticipate that the staged cut heights should remain stable temporarily
during construction. We recommend the length of the exposed cut face
be minimized during the staged construction process and the slope face
should be excavated/cut in front of the soil nailing equipment as soil
nailing progresses. All exposed cuts should be nailed the same day as
excavation occurs. Excavations should be made with care to reduce
disturbance. If caving of the cut occurs during drilling or excavation, the
nails may need to be drilled/installed though a stabilizing berm.
h. Due to the granular nature of the soils, casing may be necessary during
drilling operations. The soils behind the proposed soil nailed walls
consist of sandy fill which contains some clay which may allow the nail
borings to remain open.
I. Inspections and load tests should be accomplished (prior to and during
construction) in accordance with the previously referenced FHWA
publications and the “Pull Sheet” for Section 644 - Soil Nail Retaining
Walls.
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APPLIED GEOTECHNICAL ENGINEERING CONSULTANTS, INC. 2100948
j. The soil nail retaining walls should be constructed in accordance with
the Pull Sheet for Section 644 - Soil Nail Retaining Walls. Particular
attention should be paid to the excavation procedures as provided in
section 644.03.04 of the referenced “Pull Sheet”.
4. Fill Slopes/Embankments
We understand an embankment will be constructed to support the east
alignment of Falcon Ridge Parkway and the east end of the adjacent
roundabout. The fill depths are proposed to be approximately 14 feet tapering
down to near the existing grade at Leavitt Lane. Fill slopes constructed with
the on-site soil should be constructed no steeper than 2:1 (horizontal:vertical).
The on-site soils will be susceptible to erosion. We understand the side slopes
on either side of the embankment will be constructed at a 4:1 slope to reduce
the potential for erosion.
Fill slopes should be constructed to assure a properly compacted slope face.
This may be accomplished by wheel rolling the exposed face during grading.
As an alternative, the compacted face may be constructed by overbuilding the
slope and then cutting back the slope face to the desired grade to provide a
properly compacted slope face.
Fill placed on an existing slope should be benched into the existing slope to
provide a level surface for placement and compaction of the fill. This will also
serve to the “key” the fill into the slope and to potentially reduce differential
movement. This will be critical when placing fill to construct the east
roundabout and the east side of Mesquite Blvd. The west portion of the
roundabout is near the existing grade while the east portion requires up to
approximately 14 feet of fill. Fill should be placed in accordance with Section
203.03.12 of the NDOT Standard Specifications for Road and Bridge
Construction.
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APPLIED GEOTECHNICAL ENGINEERING CONSULTANTS, INC. 2100948
AGEC conducted analysis to estimate the potential settlement of the
embankment resulting from the densification of the underlying support soils.
The proposed embankment will support Falcon Ridge Parkway from the east
roundabout to Leavitt Lane and varies from approximately 14 feet high and
tapers down to near the existing grade at Leavitt Lane.
The estimated settlement was calculated using the Hough method for normally
consolidated, cohesionless soils and is based on a layered profile which was
developed from corrected penetration values (N160). A representative profile
was developed utilizing borings B-11, B-12 and B-13 which indicates alternating
layers of dense and very dense of sand and gravel.
The following table summarizes the estimated settlement of the embankment
depending on the fill depth:
Embankment Height (ft) Estimated Settlement (inches)*
14 1½
10 1c
5 b
*Settlement estimates assume the subgrade beneath the fill is properly prepared.
We predict the estimated settlement will occur rapidly during the construction
process due to the granular nature of the underlying support soils and should
not affect the performance of the roadway or embankment provided the fill is
properly compacted.
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APPLIED GEOTECHNICAL ENGINEERING CONSULTANTS, INC. 2100948
5. Imported Materials
In accordance with the NDOT Standard Specifications for Road and Bridge
Construction, the table below provided material specifications for soils which
will be imported site grading and structural fill.
Fill Type/Use Material Requirements
Borrow / Embankment and SiteGrading
Non-expansive granular soilR value $ 45
Selected Borrow / Embankmentand Site Grading - Surfacebeneath paved areas
Non-expansive granular soilR value $ 45Percent Passing 3" Sieve: 100
Backfill / Behind retainingwalls/below grade structuresunless granular backfill isspecified
Percent Passing 3" Sieve: 100
Granular Backfill / Behindretaining walls/below gradestructures
Percent Passing 3" Sieve: 100Percent Passing No. 4 sieve: 35 - 100Percent Passing No. 30 sieve:20 - 100Percent Passing No. 200 sieve 0 - 12LL = 35 max., PI = 10 max.pH = 5 to 9 - Concrete and steel, pH 4.0 min. - AluminumResistivity = 1000 ohm-cm min. - Concrete and steelResistivity = 500 ohm-cm min. - Aluminum
Shouldering Material Approved base aggregate - See NDOT StandardSpecifications for Bridge and Road Construction
Base Aggregate / AsphaltSupport, Concrete Slab and curbSupport
Approved base aggregate - See NDOT StandardSpecifications for Road and Bridge Construction
Base Aggregate / Drain Rock Crushed AggregatePercent Passing 2" Sieve: 100Percent Passing the No. 200 Sieve: 0-2
All materials should be free of sod and organicsLL=Liquid Limit, PI = Plasticity Index
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APPLIED GEOTECHNICAL ENGINEERING CONSULTANTS, INC. 2100948
6. Material Suitability of On-site Soils
AGEC conducted laboratory testing on soil samples obtained during our field
investigation to determine suitability for use as fill. Areas included the cut
behind the bridge abutments (Borings B-4, B-5 and B-7) and the infield cut areas
between the north bound traffic lane and the north bound off ramp (Test Pits
TP-1, TP-2 and TP-3).
The following laboratory test results were conducted by AGEC and are
provided:
AASHTO Soil Classification = A-2-4.
USCS Soil Classification = Mainly SM, and occasional SP-SM.
R-value = 64 to 75.
PI = non-plastic.
Water Soluble Sulfates = 300 to 1,200 ppm.
pH= 8.1 to 9.0.
Resistivity = 450 to 1,400 ohm-cm.
The following summary of the particle size distribution is provided:
Sieve Size Percent Passing
3" 100
No. 4 70 to 99
No. 30 56 to 98
No. 200 9 to25
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APPLIED GEOTECHNICAL ENGINEERING CONSULTANTS, INC. 2100948
Based the listed laboratory test results, the on-site soils encountered are
suitable for use as Borrow, Selected Borrow and Backfill in accordance with
Sections 203 and 207 of the NDOT Standard Specifications for Bridge and
Road Construction and “Pull Sheets” from the contract documents. Testing
indicates most of the soil tested does not meet the No. 200 sieve for Granular
Backfill and a portion of the resistivity results are too low (3 of 5 are less than
1,000). A layer of lean clay was encountered at a depth of 10 feet in Test Pit
TP-2. This layer of soil is not suitable for use as Borrow, Selected Borrow and
Backfill.
AGEC’s test results correlate with results provided in the Baseline Geotechnical
Investigation with the exception of resistivity. AGEC’s resistivity results are
generally lower in magnitude, thus indicating more corrosive soils. We
anticipate this may be due to the different test methods utilized and/or
shallower depths that AGEC’s samples were obtained. NDOT followed Nevada
test methods while AGEC followed AASHTO test methods. Further, NDOT
samples ranged from 13 to 36 feet below the existing grade while AGEC’s
samples ranged from 1 to 14 feet below the existing grade.
7. Compaction
Compaction of fill materials placed at the site should equal or exceed the
following percentages:
Area/Location Compaction
Structure foundation subgrade $ 95%
Wall backfill $ 95%
Embankment $ 90%
Pipe backfill $ 90%
Base Course $ 95%
Natural Subgrade $ 90%
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APPLIED GEOTECHNICAL ENGINEERING CONSULTANTS, INC. 2100948
Compaction of materials placed at the site should be compared to the maximum
dry density as determined by Test Method No. Nev. T101. To facilitate the
compaction process, fill should be compacted at a moisture content within 2
percent of the optimum moisture content as determined by Test Method No.
Nev. T101.
Fill placed for the project should be frequently tested to verify compaction. The
moisture content of the on-site fill soils and natural soils are varied from below
to above the optimum moisture content. Fill should be placed in loose lifts
which do not exceed 8-inches in thickness.
8. Drainage
The ground surface should be sloped to provide positive site drainage during
and following construction. Maintaining positive site drainage during and
following construction should be implemented. Ponding of water should be
minimized. Methods should also be implemented to reduce infiltration of water
into the subsurface soils behind retaining structures.
The collection and diversion of drainage away from the pavement surface is
extremely important to the satisfactory performance of the pavement section.
Proper drainage should be provided
B. Permanent Shallow Foundations
The proposed bridge overpass may be permanently supported on conventional spread
footings as provided below:
1. Bearing Resistance
Footings/foundations may designed using the factored bearing resistances
plotted on Figure 46.
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APPLIED GEOTECHNICAL ENGINEERING CONSULTANTS, INC. 2100948
The following table summarizes resistance factors used to calculate the factored
bearing resistances provided on Figure 46:
Limit State Resistance Factor (Nb)*
Service I 1.0
Strength I 0.45
Extreme Event I 1.0
*In accordance with Section 10 (specifically Sections 10.5.5.1, 10.5.5.2 and 10.5.5.3) of AASHTO LRFD
Bridge Design Specifications, 2010.
Bearing capacity analysis in the strength limit state is based a theoretical
analysis method (Section 10.6.3.1 of AASHTO LRFD Bridge Design
Specifications, 2010) for cohesionless soils. This method uses corrected
penetration values measured in the field during drilling/sampling to estimate the
soil strength (friction angle) and associated bearing capacity factors. Direct
shear data was compared the estimated soil friction angle.
The service limit state bearing values correlate to an estimated total settlement
of approximately 1 inch and a differential settlement of approximately ½ inch
after the bridge structure is placed on the permanent foundation.
Prior to placing concrete, we recommend the exposed subgrade be compacted
to at least 95 percent of the maximum dry density as determined by Test
Method No. Nev. T101.
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APPLIED GEOTECHNICAL ENGINEERING CONSULTANTS, INC. 2100948
A 12 foot wide footing was selected based on the factored bearing resistances
provided on Figure 46. With this footing width, the following table summarizes
the limit states and associated bearing resistances:
Location Bearing Soil
Limit State*
Service Limit I Strength Limit I Extreme Event I
qn
(ksf)
qr
(ksf)
qn
(ksf)
qr
(ksf)
qn
(ksf)
qr
(ksf))
All
abutments
Compacted
sand
5.5 5.5 17.8 8.0 16.5 16.5
*Where qn = nominal bearing resistance and qr = factored bearing resistance.
2. Settlement
AGEC conducted analysis to estimate the potential settlement of the
foundations to establish the Service Limit State bearing resistance resulting
densification of the underlying support soils.
The estimated settlement was calculated using the Hough method for normally
consolidated, cohesionless soils and is based on a layered profile which was
developed from corrected penetration values (N160). A representative
subsurface profile was developed based on the loosest soil conditions after
reviewing SPT values measured/corrected for AGEC Borings B-4, B-5 and B-7
and NDOT Borings RMI-1 and RMI-4. Corrected penetration values indicated
AGEC Boring B-5 contained the loosest soils. This boring profile was used to
provide a conservative settlement estimate for the subsurface conditions
encountered at various bearing pressures.
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APPLIED GEOTECHNICAL ENGINEERING CONSULTANTS, INC. 2100948
Based on the analysis described above and the proposed construction, we
estimate total settlement for the permanent foundations designed as indicated
above to be approximately 1 inch after the bridge superstructure is placed on
the permanent foundation. Differential settlement is estimated to be
approximately ½ inch. Foundation settlement will likely occur rapidly due to the
presence of granular soils supporting the foundation.
3. Footing Embedment
Spread footings should be embedded such that at least 2 feet of cover soil is
provided over the footings. This should be measured from the ground surface
to the top of the footing.
4. Foundation Base
The base of foundation excavations should be cleared of loose or deleterious
material prior to concrete placement.
5. Construction Observation
A representative of the geotechnical engineer of record should observe footing
excavations prior to concrete placement.
C. Temporary Pile Foundations
The proposed bridge super structure may be supported on temporary foundations
consisting of driven H-piles (during construction of the bridge structure) as provided
below:
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APPLIED GEOTECHNICAL ENGINEERING CONSULTANTS, INC. 2100948
1. Pile Axial Capacity
The axial capacity of the temporary piles was derived using a theoretical
analysis method for cohesionless soils. This method uses corrected penetration
values measured in the field during drilling/sampling to estimate the soil strength
(friction angle), the critical depth, skin friction parameters and the associated
bearing capacity factors.
Ultimate axial capacity curves (ultimate capacity vs depth) and ultimate uplift
capacity curves are provided on Figure 47. A depth of “0" feet on the capacity
curves shown on Figure 47 refers to the ground surface elevation at each pile.
2. Pile Length
We estimate the piles will need to be driven on the order of 25 feet to achieve
the necessary capacity.
3. Estimated Settlement
The pile settlement was estimated using 2 methods for piles bearing in the zone
of loose to medium dense sand. The first method (by Hannigan) models a
group of piles which act as a large spread footing at b the pile length (See
AASHTO LRFD Bridge Design Specifications, 2010, Section 10.7.2.3). This
method assumes the total load at the surface is transferred to this depth and
does not include skin friction capacity because of the grouped pile affect. It is
our professional opinion that this method would overestimate settlement for
piles with a relatively large spacing.
A second method (By Mindlin) was utilized to model the relatively large pile
spacing for the proposed temporary foundations. This method assumes the pile
capacity includes skin friction which varies depending on the pile spacing. This
method calculates a load or stress transferred to the tip of the pile which is
reduced due to the capacity achieved with skin friction resulting in less
estimated settlement.
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APPLIED GEOTECHNICAL ENGINEERING CONSULTANTS, INC. 2100948
With the anticipated axial loads and pile lengths, the following table summarizes
the estimated settlement for piles bearing in the underlying loose to medium
dense sand for each of the methods:
Method Estimated Total Settlement (inches) Differential
Settlement
(inch(es))Temp Abutment Temp. Support
Hannigan ¾ to 1½ ½ ½ to 1
Mindlin ½ ¼ <½
It is our professional opinion that the Mindlin method more accurately models
the proposed construction and we anticipate the settlement for piles bearing on
loose to medium dense sand will be on the order of ½ inch. This would include
the North bound abutment - south side. Tip elevations by Horrocks indicate the
piles supporting the North bound abutment - north side and both of the South
bound abutments will bear on or near the underlying dense to very dense sand.
We estimate the total settlement for these abutment piles will be less than ½
inch.
We further stress that these methods are empirical and only provide
“estimates”. The anticipated settlement may be verified/measured in the field
prior to construction by driving a pile to the design depth and conducting a load
test to measure the associated deflection under the proposed loads.
If the risk of settlement for piles bearing in the loose to medium dense sand (as
described above) is not acceptable, the piles may be driven to bear in the
underlying dense to very dense sand. The following Table summarizes the
approximate elevation where the relatively dense sand was encountered.
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APPLIED GEOTECHNICAL ENGINEERING CONSULTANTS, INC. 2100948
Boring No.Approximate elevation of dense to
very dense sand (feet)
AGEC B-4 1,586
AGEC B-5 1,580
AGEC B-7 1,591
NDOT RMI-1 1,573
NDOT RMI-4 1,575
4. Lateral Capacity
The L-pile analysis was conducted using loads provided by Horrocks Engineers
and the listed soil parameters provided in the following table to model the
subsurface profile. The parameters are based on laboratory test data and
corrected penetration values measured during sampling.
Depth (ft) Soil Type Unit wt (pcf) N (")cohesion
(psf)Kh (pci)
0-25 SM 110 37 0 130
25-55 SM 110 34 0 100
55-65 SM 110 42 0 150
65-70 ML/CL 110 0 2,000 550
Based on the L-pile analysis, we recommend a minimum pile length of 20 feet
for lateral stability. Lateral capacity curves (Pile Head Deflection, Maximum
bending moment and p-y curves) are shown on Figures 47-53.
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APPLIED GEOTECHNICAL ENGINEERING CONSULTANTS, INC. 2100948
D. Concrete Slab-on-Grade/Curb
Concrete slabs should be supported on a properly prepared and compacted subgrade
as recommended in the Subgrade Preparation and Compaction sections of this report,
pages 13-15 and 23-24, respectively.
A 4-inch layer of free-draining gravel or approved road base material should be placed
below concrete slabs for ease of construction, to promote even curing of the slab
concrete and to provide a firm and consistent subgrade.
E. Lateral Earth Pressures
1. Lateral Resistance for Footings
Lateral resistance for spread footings placed on compacted sand is controlled
by sliding resistance developed between the footing and the subgrade soil. An
ultimate friction value of 0.50 may be used in design for ultimate lateral
resistance of footings bearing on properly compacted on-site sand. Prior to
placing concrete, we recommend the exposed subgrade be compacted to at
least 95 percent of the maximum dry density as determined by Test Method No.
Nev. T101. Sliding resistance for footings should be reduced using a resistance
factor NJ=0.9.
2. Subgrade Walls and Retaining Structures
The following equivalent fluid weights are given for design of subgrade walls
and retaining structures. The active condition is where the wall moves away
from the soil. The passive condition is where the wall moves into the soil and
the at-rest condition is where the wall does not move. The values listed below
assume a horizontal surface adjacent the top and bottom of the wall.
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APPLIED GEOTECHNICAL ENGINEERING CONSULTANTS, INC. 2100948
Soil Type Active At-Rest Passive
On-site sand 35 pcf 50 pcf 300 pcf
Earth pressure coefficient 0.28 0.44 -
It should be recognized that the above values account for the lateral earth
pressures due to the soil and level backfill conditions and do not account for
hydrostatic pressures. Lateral loading should be increased to account for
surcharge loading if present above the wall and within a horizontal distance
equal to the height of the wall or if the ground surface slopes up away from the
wall.
Lateral loading should be increased to account for surcharge loading if
structures are placed above the wall and are within a horizontal distance equal
to the height of the wall or if the ground surface slopes up away from the wall.
Care should be taken to prevent percolation of surface water into the backfill
material adjacent to the retaining walls. The risk of hydrostatic buildup can be
reduced by placing subdrains behind the walls consisting of free-draining gravel
wrapped in a filter fabric. As an alternative, weep holes may be provided every
10 feet at the base of the wall to assist in drainage of water.
3. Seismic Conditions
Under seismic conditions, the equivalent fluid weight should be modified as
follows according to the Mononobe-Okabe method assuming a level backfill
condition:
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APPLIED GEOTECHNICAL ENGINEERING CONSULTANTS, INC. 2100948
Lateral Earth
Pressure Condition
Seismic Event
*PGA = 0.23g - 1,000 yr event
Active 18 pcf increase
At-rest ** 0 pcf increase
Passive 41 pcf decrease
* The PGA is adjusted for site conditions (Site Class D), but not reduced as stated on page 11-20 (AASHTO
LRFD Bridge Design Specifications) due to the critical nature of the structure.
** The total equivalent fluid weights (static plus seismic increase) in an “at-rest” condition should not exceed
the total active condition (static plus seismic increase).
We recommend the resultant from the seismic forces be placed at the mid-
height of the retaining wall in accordance with LRFD Methods.
4. Resistance Factors
The values recommended above for active and passive conditions assume
mobilization of the soil to achieve the soil strength. Appropriate resistance
factors for structural analysis for such items as overturning and sliding
resistance should be used in design.
F. Seismicity
Seismic design parameters are provided below for the 1,000 year seismic event as
requested:
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APPLIED GEOTECHNICAL ENGINEERING CONSULTANTS, INC. 2100948
Description
Seismic Event
1,000 yr event (.7% PE in 75 yrs)*
2010 AASHTO Site Class D**
Site Location Clark County, Nevada
PGA - Site Class B 0.15g
Ss (0.2 second period) - Site Class B 0.40g
S1 (1 second period) - Site Class B 0.15g
FPGA 1.50
Fa 1.48
Fv2.2
SD1 0.33g (AASHTO Seismic Zone 3)
*These values (tabulated in the 2008 NDOT Structures Manual for Clark County) are approximately equivalent to
the Site Specific (by Coordinates) 2,500 year event.
** Based on weighted average (N1)60 values and REMI survey data.
G. Liquefaction
Liquefaction is a condition where a soil loses strength due to an increase in soil pore
water pressures during a dynamic event such as an earthquake. Research indicates
that the soil type most susceptible to liquefaction during a severe seismic event is
loose, clean sand. For the sand to liquefy, it must be located beneath the groundwater
level. The liquefaction potential for soil tends to decrease with an increase in fines
content and density.
Based on our field investigation and the baseline Geotechnical Report (Reference No.
2), the following subsurface conditions exist at the subject site:
1. The groundwater level is on the order of 70 feet below the existing grade (see
Reference No. 2).
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APPLIED GEOTECHNICAL ENGINEERING CONSULTANTS, INC. 2100948
2. The subsurface soils generally consist of medium dense to very dense sand.
3. The subsurface soils located beneath approximately 30 to 50 feet are very
dense with an average (N1)60 greater than 50 blows per foot.
Based on these conditions, it is our opinion the subsurface soils above the groundwater
level are generally non-liquefiable during a severe seismic event and the soils located
beneath the groundwater level present a very low potential for liquefaction during a
severe seismic event.
H. Water Soluble Sulfates and Cement Type
Laboratory tests results indicate a water soluble sulfate concentration ranging from 300
to 1,200. According to Table 4.2.1 of ACI 318-08, the on-site soils posses a
“moderate” severity for corrosion of buried concrete structures. Therefore, we
recommend that concrete that will be in contact with the on-site soil contain Type V
sulfate resistant cement with 20% Type F pozzolan using a sulfate exposure category
of “moderate”. Further, this is in accordance with the NDOT Standard Specifications
for Road and Bridge Construction.
I. Corrosion
Corrosion tests were performed on samples of the on-site soils. Results of laboratory
tests indicate a chloride range of 14 to 161 ppm and a pH range of 8.1 to 9.0.
Resistivity tests conducted in the laboratory indicate resistivities ranging from 450 to
1,400 ohm-cm at relatively high water contents. The test results indicate the on-site
soil is corrosive to buried metal, particularly under high moisture conditions which
would result from poor drainage. Controlling drainage and infiltration into the
subsurface soils will reduce corrosion.
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APPLIED GEOTECHNICAL ENGINEERING CONSULTANTS, INC. 2100948
J. Construction Testing and Observation
We recommend testing fill and concrete materials at a frequency which meets or
exceeds project specifications NDOT Standard Specifications for Road and Bridge
Construction. We also recommend the following testing and observations be done as
a minimum.
1. Verify the subgrade is prepared as recommended beneath fill areas.
2. Conduct compaction testing on fill placed in accordance with the State of
Nevada DOT Standard Specifications for Road and Bridge Construction.
3. Verify the subgrade beneath the permanent spread footings is properly
compacted.
4. Verify the capacity of the pile foundations using PDA testing or another
approved method.
5. Conduct special inspections (concrete and steel) as required by LRFD and the
State of Nevada DOT.
A final summary report may be provided for the structures if the recommendations in
this report are followed and verified by AGEC.
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APPLIED GEOTECHNICAL ENGINEERING CONSULTANTS, INC. 2100948
LIMITATIONS
This report has been prepared in accordance with generally accepted soil and foundation
engineering practices in the area for the use of the client for design purposes. The conclusions
and recommendations included within the report are based on the information obtained from
the borings drilled at the approximate locations indicated on the site plan, the data obtained
from laboratory testing, the referenced Baseline Geotechnical Investigation and our experience
in the area. Variations in the subsurface conditions may not become evident until additional
exploration or excavation is conducted. If the proposed construction, subsurface conditions
or groundwater level is found to be significantly different from what is described above, we
should be notified to reevaluate our recommendations.
APPLIED GEOTECHNICAL ENGINEERING CONSULTANTS, INC.
Arnold DeCastro, P.E.
Reviewed by: Jared Hanks, P.E.
AD/sd P:\2010 Project Files\2010 Project Files\2100900\2100948 - West Interchange, Mesquite\2100948.report.wpd
cc Mike Dobry, P.E. - Horrocks Engineers, [email protected] Matt Horrocks, P.E. - Horrocks Engineers, [email protected] Derek Stonebraker, E.I.T. - Horrocks Engineers, [email protected]
7.58 8 8 8 8
7.56.5
7.0
8.5
10.0
13.0
16.5 16.5 16.5 16.5 16.5 16.5
6
8
10
12
14
16
18
d Be
aring Re
sistan
ce (k
sf)
Factored Bearing Resistance vs Effective Footing Width
Strength Limit State
Service Limit State ‐ Stotal = 1 inch, Sdiff = 1/2 inchExtreme Limit State
Project No. 2100948 Applied Geotech Figure 46
33.75
4.5
66.5
5.54.5 4.5 4.5
0
2
4
6
0 5 10 15 20
Factored
Effective Footing Width (ft)
Where S diff= Differential Settlement.
Note: Bearing resistances are calculated for asouthbound bottom of footing elevation (BOF) = 1,606.5 and a nouthbound BOF elevation = 1,606.0.
0
10
20
30
40
50
60
200 250 300 350 400 450 500 550
Ultimate Axial Capacity (Kips) vs Depth
HP 14X89
HP 14X117
Depth
ft
Note: "0" feet on the verticalaxis refers to the ground surface at each pile.
0
50 100 150 200 250 300
Ultimate Uplift Capacity (Kips) vs Depth
0
10
20
30
40
50
60
HP 14X89
HP 14X117
Depth
ft
Note: "0" feet on the vertical axis refers to the ground surface at each pile.
Project No. 2100948 Applied Geotech Figure 47
0.4
0.5
0.6
0.7
ead
Def
lect
ion
(inch
es)
Pile Head Deflection
Project No. 2100948 Applied Geotech Figure 48
0
0.1
0.2
0.3
0 4 8 12 16 20 24
Pile
He
Lateral Load (kips)
HP 14x89 (Strong Direction)
HP 14x89 (Weak Direction)
HP 14x117 (Strong Direction)
HP 14x117 (Weak Direction)
600
800
1000
1200
m M
omen
t (in
ch-k
ips)
Maximum Moment
Project No. 2100948 Applied Geotech Figure 49
0
200
400
0 4 8 12 16 20 24
Max
imum
Lateral Load (kips)
HP 14x89 (Strong Direction)
HP 14x89 (Weak Direction)
HP 14x117 (Strong Direction)
HP 14x117 (Weak Direction)
0
10
Dep
th (f
eet)
Pile DeflectionHP 14x89 (Strong Direction)
Project No. 2100948 Applied Geotech Figure 50
20
30-0.1 0.0 0.1 0.2 0.3 0.4 0.5 0.6 0.7
D
Deflection (inches)
3 kips
6 kips
9 kips
12 kips
15 kips
18 kips
21 kips
Lateral Load
0
10
Dep
th (f
eet)
Pile DeflectionHP 14x89 (Weak Direction)
Project No. 2100948 Applied Geotech Figure 51
20
30-0.1 0.0 0.1 0.2 0.3 0.4 0.5 0.6 0.7
D
Deflection (inches)
3 kips
6 kips
9 kips
12 kips
15 kips
18 kips
21 kips
Lateral Load
0
10
Dep
th (f
eet)
Pile DeflectionHP 14x117 (Strong Direction)
Project No. 2100948 Applied Geotech Figure 52
20
30-0.1 0.0 0.1 0.2 0.3 0.4 0.5 0.6 0.7
D
Deflection (inches)
3 kips
6 kips
9 kips
12 kips
15 kips
18 kips
21 kips
Lateral Load
0
10
Dep
th (f
eet)
Pile DeflectionHP 14x117 (Weak Direction)
Project No. 2100948 Applied Geotech Figure 53
20
30-0.1 0.0 0.1 0.2 0.3 0.4 0.5 0.6 0.7
D
Deflection (inches)
3 kips
6 kips
9 kips
12 kips
15 kips
18 kips
21 kips
Lateral Load
* Test remolded at approximately 95% compaction near the optimum moisture content.** Test conducted at its exiting moisture content and density. Page 1 of 5
Applied Geotechnical Engineering Consultants, Inc.
Table 1 - Summary of Laboratory Test Results
I-15 Milepost CL 120 Interchange Project No. 2100948
SampleLocation
NaturalMoistureContent
(%)
NaturalDry
Density(pcf)
Gradation Atterberg Limits Direct ShearMoisture-Density
Relationship
R-v
alue
@ 3
00 p
siEx
udat
ion
Pres
sure
Soil Type/ClassificationTes
t Pi
t/Bor
ing
No.
Dep
th (ft
)
Gra
vel (
%)
San
d (%
)
Silt
/Cla
y (%
)
LiquidLimit(%)
PlasticIndex(%) C
ohes
ion
(psf
)
Fric
tion
Ang
le (°)
MaximumDry
Density(pcf)
OptimumMoistureContent
(%)
TP-1 1-4 0 81 19 NP 340* 42* 122.5 11.0 64 Fill; silty sand mixed with some clay (SM); A-2-4
TP-1 3 9 106 23 Fill; silty sand mixed with some clay (SM); A-2-4
TP-1 11 8 28 Silty sand (SM); A-2-4
TP-2 1-4 15 70 15 NP 129.5 9.0 65 Fill; silty sand with gravel mixed with some clay(SM); A-2-4
TP-2 10½ 12 0 46 54 22 7 Sandy lean clay (CL); A-4
TP-3 1-4 0 81 19 NP 440* 40* 122.5 11.0 Fill; silty sand mixed with some clay (SM); A-2-4
TP-3 2½ 9 106 24 Fill; silty sand mixed with some clay (SM); A-2-4
TP-3 6 8 Fill; silty sand mixed with some clay (SM); A-2-4
TP-3 9 8 21 Fill; silty sand mixed with some clay (SM); A-2-4
TP-4 5 2 60 38 2 Poorly graded gravel with sand (GP)A-1-a
TP-5 1½ 7 102 17 Silty sand (SM); A-2-4
TP-5 4 4 101 11 Poorly graded sand with silt (SP-SM); A-2-4
TP-5 7-11 3 0 95 5 Poorly graded sand with silt (SP-SM); A-3
B-1 0-3 15 73 12 NP 128.5 7.5 67 Fill; silty sand with gravel (SM); A-2-4
Applied Geotechnical Engineering Consultants, Inc.
Table 1 - Summary of Laboratory Test Results
I-15 Milepost CL 120 Interchange Project No. 2100948
SampleLocation
NaturalMoistureContent
(%)
NaturalDry
Density(pcf)
Gradation Atterberg Limits Direct ShearMoisture-Density
Relationship
R-v
alue
@ 3
00 p
siEx
udat
ion
Pres
sure
Soil Type/ClassificationTes
t Pi
t/Bor
ing
No.
Dep
th (ft
)
Gra
vel (
%)
San
d (%
)
Silt
/Cla
y (%
)
LiquidLimit(%)
PlasticIndex(%) C
ohes
ion
(psf
)
Fric
tion
Ang
le (°)
MaximumDry
Density(pcf)
OptimumMoistureContent
(%)
* Test remolded at approximately 95% compaction near the optimum moisture content.** Test conducted at its exiting moisture content and density. Page 2 of 5
B-1 4 1 106 Poorly graded sand with silt (SP-SM); A-2-4
B-2 2½ 8 111 20 NP Fill; silty sand mixed with some clay (SM); A-2-4
B-2 5 5 110 15 Fill; silty sand mixed with some clay (SM); A-2-4
B-3 2½ 6 113 15 Fill; silty sand mixed with some clay (SM); A-2-4
B-3 5 4 109 16 NP Fill; silty sand mixed with some clay (SM); A-2-4
B-4 1-7 28 58 14 NP 550* 42* 134.0 6.5 75 Fill; silty sand with gravel mixed with some clay(SM); A-2-4
B-4 4 5 15 Fill; silty sand mixed with some clay (SM); A-2-4
B-4 6½ 780** 32** Fill; silty sand mixed with some clay (SM); A-2-4
B-4 11½ 12 108 25 Fill; silty sand mixed with some clay (SM); A-2-4
B-4 14 9 16 NP Fill; silty sand mixed with some clay (SM); A-2-4
B-4 24 8 117 19 Silty sand (SM); A-2-4
B-4 34 3 104 6 Poorly graded sand with silt (SP-SM); A-3
B-4 44 4 105 12 Poorly graded sand with silt (SP-SM); A-2-4
B-4 49 5 2 83 15 Silty sand (SM); A-2-4
Applied Geotechnical Engineering Consultants, Inc.
Table 1 - Summary of Laboratory Test Results
I-15 Milepost CL 120 Interchange Project No. 2100948
SampleLocation
NaturalMoistureContent
(%)
NaturalDry
Density(pcf)
Gradation Atterberg Limits Direct ShearMoisture-Density
Relationship
R-v
alue
@ 3
00 p
siEx
udat
ion
Pres
sure
Soil Type/ClassificationTes
t Pi
t/Bor
ing
No.
Dep
th (ft
)
Gra
vel (
%)
San
d (%
)
Silt
/Cla
y (%
)
LiquidLimit(%)
PlasticIndex(%) C
ohes
ion
(psf
)
Fric
tion
Ang
le (°)
MaximumDry
Density(pcf)
OptimumMoistureContent
(%)
* Test remolded at approximately 95% compaction near the optimum moisture content.** Test conducted at its exiting moisture content and density. Page 3 of 5
B-4 54 6 110 13 Silty sand (SM); A-2-4
B-4 64 14 105 51 Sandy fat clay (CH); A-7-5
B-5 1-7 25 66 9 NP 490* 42* 130.5 7.5 Fill; poorly graded sand with silt and gravel mixedwith some clay (SP-SM); A-3
B-5 4 6 108 13 NP Fill; silty sand mixed with some clay (SM); A-2-4
B-5 9 6 1 83 16 Fill; silty sand mixed with some clay (SM); A-2-4
B-5 11½ 6 109 15 Fill; silty sand mixed with some clay (SM); A-2-4
B-5 24 6 113 15 Fill; silty sand mixed with some clay (SM); A-2-4
B-5 34 350* 33* Silty sand (SM); A-2-4
B-5 39 4 9 Poorly graded sand with silt (SP-SM); A-3
B-5 44 2 112 9 Poorly graded sand with silt (SP-SM); A-3
B-5 59 9 25 Silty sand (SM); A-2-4
B-6 6½ 5 102 10 NP Poorly graded sand with silt (SP-SM); A-3
B-6 11½ 6 101 15 Silty sand (SM); A-2-4
B-6 16½ 4 106 8 Poorly graded sand with silt (SP-SM) A-3
Applied Geotechnical Engineering Consultants, Inc.
Table 1 - Summary of Laboratory Test Results
I-15 Milepost CL 120 Interchange Project No. 2100948
SampleLocation
NaturalMoistureContent
(%)
NaturalDry
Density(pcf)
Gradation Atterberg Limits Direct ShearMoisture-Density
Relationship
R-v
alue
@ 3
00 p
siEx
udat
ion
Pres
sure
Soil Type/ClassificationTes
t Pi
t/Bor
ing
No.
Dep
th (ft
)
Gra
vel (
%)
San
d (%
)
Silt
/Cla
y (%
)
LiquidLimit(%)
PlasticIndex(%) C
ohes
ion
(psf
)
Fric
tion
Ang
le (°)
MaximumDry
Density(pcf)
OptimumMoistureContent
(%)
* Test remolded at approximately 95% compaction near the optimum moisture content.** Test conducted at its exiting moisture content and density. Page 4 of 5
B-7 1½ 6 11 65 24 Fill; silty sand mixed with some clay (SM); A-2-4
B-7 6½ 5 3 80 17 NP Fill; silty sand mixed with some clay (SM); A-2-4
B-7 9 5 111 17 Fill; silty sand mixed with some clay (SM); A-2-4
B-7 16½ 8 1 83 16 Fill; silty sand mixed with some clay (SM); A-2-4
B-7 24 4 109 11 Fill; silty sand mixed with some clay (SM); A-2-4
B-7 34 4 8 Poorly graded sand with silt (SP-SM); A-3
B-7 39 3 106 8 Poorly graded sand with silt (SP-SM); A-3
B-7 44 14 56 Sandy lean clay (CL); A-4
B-7 54 5 108 10 Poorly graded sand with silt (SP-SM): A-3
B-7 59 5 7 Poorly graded sand with silt (SP-SM); A-3
B-7 69 10 108 16 Silty sand (SM); A-2-4
B-8 5 4 105 21 Fill; silty sand mixed with some clay (SM); A-2-4
B-8 7½ 3 103 17 Fill; silty sand mixed with some clay (SM); A-2-4
B-9 6½ 5 105 15 Fill; silty sand mixed with some clay (SM); A-2-4
B-10 6½ 5 103 6 Poorly graded sand with silt (SP-SM); A-3
Applied Geotechnical Engineering Consultants, Inc.
Table 1 - Summary of Laboratory Test Results
I-15 Milepost CL 120 Interchange Project No. 2100948
SampleLocation
NaturalMoistureContent
(%)
NaturalDry
Density(pcf)
Gradation Atterberg Limits Direct ShearMoisture-Density
Relationship
R-v
alue
@ 3
00 p
siEx
udat
ion
Pres
sure
Soil Type/ClassificationTes
t Pi
t/Bor
ing
No.
Dep
th (ft
)
Gra
vel (
%)
San
d (%
)
Silt
/Cla
y (%
)
LiquidLimit(%)
PlasticIndex(%) C
ohes
ion
(psf
)
Fric
tion
Ang
le (°)
MaximumDry
Density(pcf)
OptimumMoistureContent
(%)
B-10 9 3 99 13 Silty sand (SM); A-2-4
B-11 1½ 2 126 5 Poorly graded sand with silt and gravel (SP-SM);A-3
B-11 9-11 3 71 23 6 Poorly graded gravel with sand (GP); A-1-a
B-11 11½ 9 97 Silty sand (SM); A-2-4
B-11 14 17 111 69 Sandy fat clay (CH); A-7-5
B-12 3-5 4 19 76 5 Poorly graded sand with silt and Gravel (SP-SM);A-1-b
B-12 6½ 3 92 4 Poorly graded gravel with sand (GP)A-1-a
B-12 9 7 110 15 Silty sand (SM); A-2-4
B-12 24 5 101 4 Poorly graded sand (SP); A-3
B-12 34 8 104 10 Poorly graded sand with silt (SP-SM); A-3
B-13 4 2 4 Poorly graded gravel (GP); A-1-a
B-13 19 4 101 7 Poorly graded sand with silt (SP-SM); A-3
B-13 29 21 99 92 58 39 Fat clay (CH); A-7-5
* Test remolded at approximately 95% compaction near the optimum moisture content.** Test conducted at its exiting moisture content and density.
Page 5 of 5
APPLIED GEOTECHNICAL ENGINEERING CONSULTANTS, INC.
TABLE 2SUMMARY OF CHEMICAL LABORATORY TEST RESULTS
I-15 Milepost CL 120 Interchange Project No. 2100948
SAMPLE LOCATIONCHLORIDE
(PPM)pH RESISTIVITY
(OHM-CM)
WATER SOLUBLESULFATES
(PPM)
SAMPLE CLASSIFICATIONTEST PIT/
BORING #DEPTH(FEET)
TP-1 1-4 32 8.6 1,400 300 Fill; silty sand mixed with some clay (SM); A-2-4
TP-2 1-4 83 8.3 450 500 Fill; silty sand with gravel mixed with some clay (SM); A-2-4
TP-3 1-4 14 8.5 800 400 Fill; silty sand mixed with some clay (SM); A-2-4
B-2 10 300 Fill; silty sand mixed with some clay (SM); A-2-4
B-3 7½ 9.0 Fill; silty sand mixed with some clay (SM); A-2-4
B-3 10 33 Fill; silty sand mixed with some clay (SM); A-2-4
B-4 1-7 11 8.2 1,070 Fill; silty sand mixed with some clay (SM); A-2-4
B-5 1-7 8.2 870 Fill; silty sand mixed with some clay (SM); A-2-4
B-5 14 35 500 Fill; silty sand mixed with some clay (SM); A-2-4
B-6 4 400 Fill; silty sand mixed with some clay (SM); A-2-4
B-7 9 25 8.1 400 Fill; silty sand mixed with some clay (SM); A-2-4
B-9 1½ 161 1,200 Fill; silty sand mixed with some clay (SM); A-2-4