Soil Mechanics Report

7/25/2019 Soil Mechanics Report

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Soil Mechanics


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Soil Mechanics-324L Project

Background

Slope stability is the susceptibility of soil covered slopes to potential movement.The shear stress, factor responsible to the downward pull of the slope, is resisted

by shear strength, factors such as friction or interactions of the materials of the

soil, and thus slope stability is the stability of the two. Basic factors as well at

environmental factors effect these aspects of shear.

The main factor in which soil moves upon a slope is gravity. The downward pull ofgravity is what makes the shear stress in slope stability. When this force becomes

greater than the shear strength that is the moment in which movement occurs.

However it is important to include consideration to anything that reduces this

shear strength, often expressed as the safety factor. Variables of which include,

the angle of internal friction for the soil, the slope angle, the buoyant unit weight

of soil and saturated unit weight of soil.

Soil is prone to environmental factors and these effect slope stability, such

include water, different earth materials, weak structures, weathering, and natural

disasters. Water can seep into the soil and add weight to it (since weight is force

and force is stress divided by area), change its shape (effect the area), angle of the

slope (angle of repose: the steepest angle at which a pile of unconsolidated grains

remains stable) and friction of material Different materials may have different


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Countermeasures

One of the many countermeasures that can be taken is head excavation. This is

the process of diggingout soil at the top or head of the slope. The removal of

soil at the top of the slope can take away some of the pressure caused by the

weight of the soil. This ensures that the unsteady soil will not slide.

Toe Loading and a retaining wall are options for the end point of the slope.

Increasing the load being applied to the end or toe of the slope can increase the

stability of the soil. The retaining wall can hold back any soil that may slip during a

landslide. Average retaining walls range from nine to ten meters. Both

countermeasures will increase stability at the bottom of the slope.

Implant of a drain is another important measure that can be implemented to

reduce any slipping of soil. If a drainage pipe is placed within the slope, then any

unwanted moisture could be extracted. Drains placed throughout the slope can

cause a lowering of the water table as well, to increase the safety factor. This

countermeasure is most useful in clay soil, due to cohesion.


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Group #2

Modified Data Sheet Retaining Wall

FS = 1.52

18 c 2 10

10

slice X Y surface Y water Y ground b hs hw hsave hwave W u Wcos() Wsin() L U Wcos()-U

1 0 22.476 13.476 13.476 -9 -9

2 10 22.476 15. 8218 1 5.8218 10 - 6. 6542 - 6.6542 - 7. 8271 - 7.8271 1408. 88 0 - 78. 271 1408. 878 0.00 10. 00 - 782. 71 2191. 59

3 20 22.476 18.165 15.135 10 -7.34 -4.31 -7.00 -5.48 1259.57 0.00 -54.83 1259.57 0.00 10.00 -548.26 1807.83

4 30 22.476 19.3662 14.1464 10 -8.33 -3.11 -7.84 -3.71 1410.35 0.00 -37.10 1410.35 0.00 10.00 -371.04 1781.39

5 40 22.476 20.2043 13.4227 10 -9.05 -2.27 -8.69 -2.69 1564.46 0.00 -26.91 1564.46 0.00 10.00 -269.08 1833.54

6 50 22.476 20.6102 13.3874 10 -9.09 -1.87 -9.07 -2.07 1632.77 0.00 -20.69 1632.77 0.00 10.00 -206.88 1839.65

7 60 22.476 21.7626 13.3521 10 -9.12 -0.71 -9.11 -1.29 1639.13 0.00 -12.90 1639.13 0.00 10.00 -128.96 1768.09

8 70 24.3394 2 3.7816 1 3.3379 10 -11.00 - 0.56 -10.06 -0.64 1811.29 10.56 -6.36 1780.64 331.80 10.17 -64.65 1845.29

9 80 28.9858 25.1571 13.3379 10 -15.65 - 3.83 -13.32 -2.19 2398.45 24.92 -21.93 2175.12 1010.65 11.03 - 241.84 2416.96

10 90 20.1258 2 7.6141 1 3.5761 10 -6.55 7.49 -11.10 1.83 1997.78 -41.54 18.30 1495.31 -1324.84 13.36 244.47 1250.8411 100 30.9771 30.2858 14.3719 10 -16.61 - 0.69 -11.58 3.40 2083.94 47.34 33.99 1412.23 1532.45 14.76 501.50 910.74

12 110 33.4259 32.0516 16.8856 10 -16.54 - 1.37 -16.57 -1.03 2983.10 13.76 -10.33 2897.48 709.54 10.30 - 106.33 3003.82

13 120 34.6997 33.2166 19.4659 10 -15.23 - 1.48 -15.89 -1.43 2859.67 7.26 -14.29 2836.75 361.34 10.08 - 144.02 2980.77

14 130 35.9914 34.6684 23.4469 10 -12.54 - 1.32 -13.89 -1.40 2500.05 7.36 -14.03 2479.45 320.27 10.08 - 141.47 2620.92

15 140 36.7967 36.4114 28.2537 10 -8.54 - 0.39 -10.54 -0.85 1897.88 4.60 -8.54 1891.75 152.34 10.03 -85.69 1977.44

16 150 39.5005 39.0714 33.9885 10 -5.51 - 0.43 -7.03 -0.41 1264.95 15.13 -4.07 1221.10 330.16 10.36 -42.18 1263.28

17 160 43.9523 43.6754 41.2023 10 -2.75 -0.28 -4.13 -0.35 743.58 24.00 -3.53 679.31 302.41 10.95 -38.64 717.95

18 170 51.5188 4 9.3993 5 1.5188 10 0.00 -2.12 -1.38 -1.20 247.50 37.11 -11.98 197.37 149.34 12.54 -150.25 347.62

19 180 52.8032 52.0931 52.8032 10 0.00 -0.71 0.00 -1.41 0.00 7.32 -14.15 0.00 0.00 10.08 -142.64 142.64

20 190 53.0693 53.0693 53.0693 10 0.00 0.00 0.00 -0.36 0.00 1.52 -3.55 0.00 0.00 10.00 -35.52 35.52

21 200 57.8349 55.229 57.8349 10 0.00 -2.61 0.00 -1.30 0.00 25.48 -13.03 0.00 0.00 11.08 -144.33 144.33

3875.47 214.82 30880.20


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25 m

50 m

Water level

Surface

Sliding

Mudsto

Slope A

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17

10 m

Distance (m)

200 m (20 slices @10m)TYP

ODUCED

BY

AN

AUTODESK

EDUCATIONA

LPRODUCT

PRODUCED BY AN AUTODESK EDUCATIONAL PRODUCT


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MODIFIED SLOPE A

25 m

50 m

Water level

Surface

Sliding

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16

10 m

Vertical Distance (m)

200 m (20 slices @10m)TYP

9m

ODUCED

BY

AN

AUTODESK

EDUCATIONA

LPRODUCT

PRODUCED BY AN AUTODESK EDUCATIONAL PRODUCT


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BACKGROUND

Slope Stability is the susceptibility of soil covered slopes, to potential

movement.

This can be composed of a downward force, shear stress, or an upward force,

shear strength.


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B CKGROUND (CONTD)

Gravity is the greatest factor in which soil moves.

The downward pull of gravity creates shear stress.

Environmental factors that can cause weak stability include earth and rock-

filled dams, embankments, and excavated slopes.


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EFFECTS OF LANDSLIDES


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EFFECTS OF LANDSLIDES CONTD)


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CALIFORNIA LANDSLIDE

http://losangeles.cbslocal.com/2014/12/03/stretch-of-pch-shut-by-mudslides-may-reopen-thursday/

Occurred Sunday November 30th, 2014

Occurred on PCH due to heavily saturated soil.
http://losangeles.cbslocal.com/2014/12/03/stretch-of-pch-shut-by-mudslides-may-reopen-thursday/http://losangeles.cbslocal.com/2014/12/03/stretch-of-pch-shut-by-mudslides-may-reopen-thursday/http://losangeles.cbslocal.com/2014/12/03/stretch-of-pch-shut-by-mudslides-may-reopen-thursday/http://losangeles.cbslocal.com/2014/12/03/stretch-of-pch-shut-by-mudslides-may-reopen-thursday/http://losangeles.cbslocal.com/2014/12/03/stretch-of-pch-shut-by-mudslides-may-reopen-thursday/http://losangeles.cbslocal.com/2014/12/03/stretch-of-pch-shut-by-mudslides-may-reopen-thursday/http://losangeles.cbslocal.com/2014/12/03/stretch-of-pch-shut-by-mudslides-may-reopen-thursday/http://losangeles.cbslocal.com/2014/12/03/stretch-of-pch-shut-by-mudslides-may-reopen-thursday/http://losangeles.cbslocal.com/2014/12/03/stretch-of-pch-shut-by-mudslides-may-reopen-thursday/http://losangeles.cbslocal.com/2014/12/03/stretch-of-pch-shut-by-mudslides-may-reopen-thursday/http://losangeles.cbslocal.com/2014/12/03/stretch-of-pch-shut-by-mudslides-may-reopen-thursday/http://losangeles.cbslocal.com/2014/12/03/stretch-of-pch-shut-by-mudslides-may-reopen-thursday/http://losangeles.cbslocal.com/2014/12/03/stretch-of-pch-shut-by-mudslides-may-reopen-thursday/http://losangeles.cbslocal.com/2014/12/03/stretch-of-pch-shut-by-mudslides-may-reopen-thursday/http://losangeles.cbslocal.com/2014/12/03/stretch-of-pch-shut-by-mudslides-may-reopen-thursday/http://losangeles.cbslocal.com/2014/12/03/stretch-of-pch-shut-by-mudslides-may-reopen-thursday/http://losangeles.cbslocal.com/2014/12/03/stretch-of-pch-shut-by-mudslides-may-reopen-thursday/http://losangeles.cbslocal.com/2014/12/03/stretch-of-pch-shut-by-mudslides-may-reopen-thursday/http://losangeles.cbslocal.com/2014/12/03/stretch-of-pch-shut-by-mudslides-may-reopen-thursday/http://losangeles.cbslocal.com/2014/12/03/stretch-of-pch-shut-by-mudslides-may-reopen-thursday/


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CANADA LANDSLIDE

http://www.thespec.com/news-story/5161560-update-403-has-reopened-

to-traffic-after-being-closed-10-hours-from-landslide-motorists-resigned/


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ORDINARY METHOD OF SLICE

Most commonly used method for stability analysis.

The soil above the trial failure surface is divided intoseveral vertical slices. (Slices do not need to be the same

length)

Then consider the unit length of each slice and analyze the

forces acting upon it.


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SLOPE STABILITY ANALYSIS

CURRENT CONDITION

Safety Factor =


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SLOPE STABILITY ANALYSISCURRENT CONDITION

=(+

)

= 1.16 < 1.5 (N.G)


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PRELIMINARY DESIGNWATER LINE LOWERED 1 METER

=(+

)

= 1.24 < 1.5 (N.G)


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PRELIMINARY DESIGN9 METER RETAINING WALL & WATER LINE LOWERED 1 METER

=(+

)

= 1.60 > 1.5 (OK)


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SAFE DESIGN9 METER WALL WITH STANDARD WATER LINE

=(+

)

= 1.52


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ALTERNATIVE METHODS

Head Excavation

Process of digging out soil at the top or head of a slope.

This process takes away some pressure caused by the weight of the soil.


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LTERN TIVE METHODS (CONTD)

Implant of a Drain

This process involves placing a drainage pipe within the slope.

This allows moisture to be extracted and lowers the water table.

Most useful in clay soil.


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CONCLUSION

For the safety factor of 1.56, the countermeasure taken is a retaining wall 9

meters high.

THANK YOU FOR YOUR TIME!


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RESOURCES

Picture on slide 7 http://www.thespec.com/news-story/5161560-update-403-has-

reopened-to-traffic-after-being-closed-10-hours-from-landslide-motorists-resigned/

Link on slide 6 http://losangeles.cbslocal.com/2014/12/03/stretch-of-pch-shut-by-

mudslides-may-reopen-thursday/ Pictures on slide 10 CoursePack

Picture on slide 5 http://www.getemergencyprepared.com/landslide

Picture on slide 4 http://america.aljazeera.com/articles/2013/9/16/mexico-pummeled-

by2majorstorms.html

Picture on slide 17 and 18 are from Article: Appendix C. Introduction to LandslideStabilization and Mitigation
http://www.thespec.com/news-story/5161560-update-403-has-reopened-to-traffic-after-being-closed-10-hours-from-landslide-motorists-resigned/http://www.thespec.com/news-story/5161560-update-403-has-reopened-to-traffic-after-being-closed-10-hours-from-landslide-motorists-resigned/http://losangeles.cbslocal.com/2014/12/03/stretch-of-pch-shut-by-mudslides-may-reopen-thursday/http://losangeles.cbslocal.com/2014/12/03/stretch-of-pch-shut-by-mudslides-may-reopen-thursday/http://www.getemergencyprepared.com/landslidehttp://america.aljazeera.com/articles/2013/9/16/mexico-pummeled-by2majorstorms.htmlhttp://america.aljazeera.com/articles/2013/9/16/mexico-pummeled-by2majorstorms.htmlhttp://america.aljazeera.com/articles/2013/9/16/mexico-pummeled-by2majorstorms.htmlhttp://america.aljazeera.com/articles/2013/9/16/mexico-pummeled-by2majorstorms.htmlhttp://america.aljazeera.com/articles/2013/9/16/mexico-pummeled-by2majorstorms.htmlhttp://america.aljazeera.com/articles/2013/9/16/mexico-pummeled-by2majorstorms.htmlhttp://america.aljazeera.com/articles/2013/9/16/mexico-pummeled-by2majorstorms.htmlhttp://america.aljazeera.com/articles/2013/9/16/mexico-pummeled-by2majorstorms.htmlhttp://america.aljazeera.com/articles/2013/9/16/mexico-pummeled-by2majorstorms.htmlhttp://www.getemergencyprepared.com/landslidehttp://losangeles.cbslocal.com/2014/12/03/stretch-of-pch-shut-by-mudslides-may-reopen-thursday/http://losangeles.cbslocal.com/2014/12/03/stretch-of-pch-shut-by-mudslides-may-reopen-thursday/http://losangeles.cbslocal.com/2014/12/03/stretch-of-pch-shut-by-mudslides-may-reopen-thursday/http://losangeles.cbslocal.com/2014/12/03/stretch-of-pch-shut-by-mudslides-may-reopen-thursday/http://losangeles.cbslocal.com/2014/12/03/stretch-of-pch-shut-by-mudslides-may-reopen-thursday/http://losangeles.cbslocal.com/2014/12/03/stretch-of-pch-shut-by-mudslides-may-reopen-thursday/http://losangeles.cbslocal.com/2014/12/03/stretch-of-pch-shut-by-mudslides-may-reopen-thursday/http://losangeles.cbslocal.com/2014/12/03/stretch-of-pch-shut-by-mudslides-may-reopen-thursday/http://losangeles.cbslocal.com/2014/12/03/stretch-of-pch-shut-by-mudslides-may-reopen-thursday/http://losangeles.cbslocal.com/2014/12/03/stretch-of-pch-shut-by-mudslides-may-reopen-thursday/http://losangeles.cbslocal.com/2014/12/03/stretch-of-pch-shut-by-mudslides-may-reopen-thursday/http://losangeles.cbslocal.com/2014/12/03/stretch-of-pch-shut-by-mudslides-may-reopen-thursday/http://losangeles.cbslocal.com/2014/12/03/stretch-of-pch-shut-by-mudslides-may-reopen-thursday/http://losangeles.cbslocal.com/2014/12/03/stretch-of-pch-shut-by-mudslides-may-reopen-thursday/http://losangeles.cbslocal.com/2014/12/03/stretch-of-pch-shut-by-mudslides-may-reopen-thursday/http://losangeles.cbslocal.com/2014/12/03/stretch-of-pch-shut-by-mudslides-may-reopen-thursday/http://losangeles.cbslocal.com/2014/12/03/stretch-of-pch-shut-by-mudslides-may-reopen-thursday/http://www.thespec.com/news-story/5161560-update-403-has-reopened-to-traffic-after-being-closed-10-hours-from-landslide-motorists-resigned/http://www.thespec.com/news-story/5161560-update-403-has-reopened-to-traffic-after-being-closed-10-hours-from-landslide-motorists-resigned/http://www.thespec.com/news-story/5161560-update-403-has-reopened-to-traffic-after-being-closed-10-hours-from-landslide-motorists-resigned/http://www.thespec.com/news-story/5161560-update-403-has-reopened-to-traffic-after-being-closed-10-hours-from-landslide-motorists-resigned/http://www.thespec.com/news-story/5161560-update-403-has-reopened-to-traffic-after-being-closed-10-hours-from-landslide-motorists-resigned/http://www.thespec.com/news-story/5161560-update-403-has-reopened-to-traffic-after-being-closed-10-hours-from-landslide-motorists-resigned/http://www.thespec.com/news-story/5161560-update-403-has-reopened-to-traffic-after-being-closed-10-hours-from-landslide-motorists-resigned/http://www.thespec.com/news-story/5161560-update-403-has-reopened-to-traffic-after-being-closed-10-hours-from-landslide-motorists-resigned/http://www.thespec.com/news-story/5161560-update-403-has-reopened-to-traffic-after-being-closed-10-hours-from-landslide-motorists-resigned/http://www.thespec.com/news-story/5161560-update-403-has-reopened-to-traffic-after-being-closed-10-hours-from-landslide-motorists-resigned/http://www.thespec.com/news-story/5161560-update-403-has-reopened-to-traffic-after-being-closed-10-hours-from-landslide-motorists-resigned/http://www.thespec.com/news-story/5161560-update-403-has-reopened-to-traffic-after-being-closed-10-hours-from-landslide-motorists-resigned/http://www.thespec.com/news-story/5161560-update-403-has-reopened-to-traffic-after-being-closed-10-hours-from-landslide-motorists-resigned/http://www.thespec.com/news-story/5161560-update-403-has-reopened-to-traffic-after-being-closed-10-hours-from-landslide-motorists-resigned/http://www.thespec.com/news-story/5161560-update-403-has-reopened-to-traffic-after-being-closed-10-hours-from-landslide-motorists-resi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Documents

Soil Mechanics Report