1. RETAINING EARTH STRUCTURE Session 11 – 16
Course : S0825/Foundation Engineering
Year : 2009
RETAINING EARTH STRUCTURE Session 11 – 16

2. RETAINING EARTH STRUCTURE
Topic:
Lateral Earth Pressure
General
Active earth pressure
Rankine earth pressure
Coulomb earth pressure
Lateral earth pressure due to surcharge
Passive earth pressure
Influence of ground water table
Sheet Pile Structure
Types of Sheet Pile
Lateral Pressure Diagram
Cantilever Sheet Pile
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3. LATERAL EARTH PRESSURE
SESSION 11 – 12
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4. GENERAL
Lateral earth pressure represents pressures that are “to the side” (horizontal) rather than vertical.
Caused by soil self weight and or external load
3 categories:
At rest earth pressure
Active earth pressure
Passive earth pressure
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5. AT REST EARTH PRESSURE
The at rest pressure develops when the wall experiences no lateral movement. This typically occurs when the wall is restrained from movement such as a basement wall that is supported at the bottom by a slab and at the top by a floor framing system prior to placing soil backfill against the wall.
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6. ACTIVE EARTH PRESSURE
The active pressure develops when the wall is free to move outward such as a typical retaining wall and the soil mass stretches sufficiently to mobilize its shear strength.
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7. PASSIVE EARTH PRESSURE
If the wall moves into the soil, then the soil mass is compressed
sufficiently to mobilize its shear strength and the passive pressure develops.
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8. AT REST EARTH PRESSURE Jaky, Broker and Ireland  Ko = M – sin ’q
Jaky, Broker and Ireland  Ko = M – sin ’
Sand, normally consolidated clay  M = 1
Clay with OCR > 2  M = 0.95
v =  . z + q z
Broker and Ireland v
Ko = PI , 0  PI  40
Ko = PI , 40  PI  80 h
Sherif and Ishibashi  Ko =  +  (OCR – 1)
 = (LL – 20)
= (LL – 20)
LL > 110%   = 1.0 ;  = 0.19
At rest, K = Ko
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9. ACTIVE EARTH PRESSURE
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10. RANKINE ACTIVE EARTH PRESSURE
1 = 3 . tan2 (45+/2)+2c.tan (45+/2)
a = v . tan2(45-/2) – 2c . tan (45-/2)
a = v . Ka – 2cKa
Ka = tan2 (45 - /2)
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11. RANKINE ACTIVE EARTH PRESSURE (INCLINED BACKFILL)
(for granular soil, c = 0)
For c- soil
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12. COULOMB ACTIVE EARTH PRESSURE
Assumptions:
Fill material is granular soil
Friction of wall and fill material is considered
Soil failure shape is plane (BC1, BC2 …)
Pa = ½ Ka .  . H2
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13. COULOMB ACTIVE EARTH PRESSURE (SURCHARGE ON BACKFILL)
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14. RANKINE PASSIVE EARTH PRESSURE
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15. RANKINE PASSIVE EARTH PRESSURE
p= v . tan2(45+/2) + 2c . tan (45+/2)
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16. RANKINE PASSIVE EARTH PRESSURE
Kp = tan2 (45 + /2)
h = v . Kp + 2cKp
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17. COULOMB PASSIVE EARTH PRESSURE
Pp = ½ Kp .  . H2
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18. LATERAL EARTH PRESSURE DUE TO SURCHARGE
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19. LATERAL EARTH PRESSURE DUE TO SURCHARGE
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20. PURPOSE OF LATERAL EARTH PRESSURE
STABILITY ANALYSIS GRAVITY WALL AGAINST
SLIDING
OVERTURNING
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21. PURPOSE OF LATERAL EARTH PRESSURE
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22. PURPOSE OF LATERAL EARTH PRESSURE
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23. SHEET PILE STRUCTURES
SESSION 13 – 14
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24. SHEET PILE
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25. GENERAL
Connected or semi-connected sheet piles are often used to build continuous walls to retain the lateral pressure caused by soil or external load.
In contrast to the construction of other types of retaining wall, the building of sheet pile walls do not usually require dewatering the site.
Sheet piles are also used for some temporary structures, such as braced cut.
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26. SHEET PILE TYPES (CANTILEVER)
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27. SHEET PILE TYPES (ANCHORED)
Free Earth Support
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28. SHEET PILE TYPES (ANCHORED)
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Fixed Earth Support

29. SHEET PILE TYPES (ANCHORED)
anchor plate or beam
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30. SHEET PILE TYPES (ANCHORED)
tie back
vertical anchor pile
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31. anchor beam with batter piles
SHEET PILE TYPES (ANCHORED)
anchor beam with batter piles
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32. LATERAL EARTH PRESSURE DIAGRAM
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33. LATERAL EARTH PRESSURE DIAGRAM
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34. LATERAL EARTH PRESSURE DIAGRAM
Fixed Earth Support
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35. LATERAL EARTH PRESSURE DIAGRAM
Free Earth Support
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36. LATERAL EARTH PRESSURE DIAGRAM
Free Earth Support
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37. CALCULATION STEPS CANTILEVER SHEET PILE - SAND
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38. CALCULATION STEPS CANTILEVER SHEET PILE - SAND
1. Determine the value of Ka and Kp
2. Calculate p1and p2 with L1 and L2 are known
3. Calculate L3
4. Calculate the resultant of the area ACDE (P)
5. Determine the z (the center of pressure for the area ACDE)
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39. CALCULATION STEPS CANTILEVER SHEET PILE - SAND
6. Calculate p5
7. Calculate A1, A2, A3, A4
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40. CALCULATION STEPS CANTILEVER SHEET PILE - SAND
8. Determine L4
9. Calculate p4
10. Calculate p3
11. Calculate L5
12. Draw the pressure distribution diagram
13. Obtain the theoretical depth ; D = L3 + L4
The actual depth of penetration is increased by about 20% - 30%
14. Calculate the maximum bending moment
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41. EXAMPLE CANTILEVER SHEET PILE - SAND
GWL
d = 15.9 kN/m3
t = kN/m3
= 32o
c = 0 kPa
L1 = 2 m
L2 = 3 m D
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Determine the penetration depth (D) and dimension of sheet pile

42. EXAMPLE CANTILEVER SHEET PILE - SAND
Step 1 (determine the value of ka and kp)
Step 2 (calculate p1 and p2)
Step 3 (Calculate L3)
kPa
kPa m
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43. EXAMPLE CANTILEVER SHEET PILE - SAND
Step 4 (calculate P)
Step 5 (calculate z)
Step 6 (calculate p5)
kN/m m
kN/m2
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44. EXAMPLE CANTILEVER SHEET PILE - SAND
Step 7 (calculate A1 – A4)
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45. EXAMPLE CANTILEVER SHEET PILE - SAND
Step 8 (determine L4)
Step 9 (calculate p4)
Step 10 (calculate p3)
L4  4.8 m
kPa
kPa
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46. EXAMPLE CANTILEVER SHEET PILE - SAND
Step 11 (Calculate L5)
Step 12
Draw the pressure distribution diagram
Step 13 (the penetration dept of sheet pile)
Theoretical = = 5.46 m
Actual = 1.3 (L3+L4) =7.1 m m
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47. EXAMPLE CANTILEVER SHEET PILE - SAND
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48. EXAMPLE CANTILEVER SHEET PILE - SAND
Dimension of Sheet Pile m
kN.m
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49. SHEET PILE STRUCTURE
SESSION 15 – 16
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50. CALCULATION STEPS CANTILEVER SHEET PILE - CLAY
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51. CALCULATION STEPS CANTILEVER SHEET PILE - CLAY
1. Determine the value of Ka and Kp
In case of saturated soft clay with internal friction angle () = 0, we got
Ka = Kp = 1
2. Calculate p1and p2 with L1 and L2 are known
3. Calculate the resultant of the area ACDE (P1) and z1 (the center of pressure for the area ACDE)
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52. CALCULATION STEPS CANTILEVER SHEET PILE - CLAY
4. Calculate the theoretical penetration depth of sheet pile (D)
5. Calculate L4
6. Calculate p6 and p7
7. Obtain the actual penetration depth of sheet pile
Dactual = (1.4 – 1.6) x Dtheoretical
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53. CALCULATION STEPS CANTILEVER SHEET PILE - CLAY
8. Calculate the maximum bending moment
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54. EXAMPLE CANTILEVER SHEET PILE - CLAY
L1 = 2 m
L2 = 3 m
sand
GWL
d = 15.9 kN/m3
t = kN/m3
= 32o
c = 0 kPa
Clay D
cu = 47 kPa
 = 0 o
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Determine the penetration depth (D) and dimension of sheet pile

55. EXAMPLE CANTILEVER SHEET PILE - CLAY
Step 1 (Determine ka and kp)
Step 2 (calculate p1 and p2)
Step 3 (calculate P1 and z1)
kPa
kPa
kN/m m
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56. EXAMPLE CANTILEVER SHEET PILE - CLAY
Step 4 (obtain Dtheoretical)
Step 5 (calculate L4)
D = 2.13 m
L4 = 2.13 m
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57. EXAMPLE CANTILEVER SHEET PILE - CLAY
Step 6 (calculate p6 and p7)
Step 7 (draw the lateral diagram)
Step 8 (Obtain Dactual)
kN/m2
Dactual = 1.5 x Dtheorical = 1.5 x 2.13 = 3.2 m
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58. EXAMPLE CANTILEVER SHEET PILE - CLAY
Calculation of moment
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59. CALCULATION STEPS ANCHORED SHEET PILE – FREE – SAND
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60. CALCULATION STEPS ANCHORED SHEET PILE – FREE – SAND
1. Determine the value of Ka and Kp
2. Calculate p1and p2 with L1 and L2 are known
3. Calculate L3
4. Calculate P as a resultant of area ACDE
5. Determine the center of pressure for the area ACDE ( z )
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61. CALCULATION STEPS ANCHORED SHEET PILE – FREE – SAND
6. Calculate L4
Determination of penetration depth of sheet pile (D)
Dtheoretical = L3 + L4
Dactual = (1.3 – 1.4) Dtheoretical
Determination of anchor force
F = P – ½ [’(Kp – Ka)]L42
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62. CALCULATION STEPS ANCHORED SHEET PILE – FREE – CLAY
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63. CALCULATION STEPS ANCHORED SHEET PILE – FREE – CLAY
1. Determine the value of Ka and Kp
In case of saturated soft clay with internal friction angle () = 0, we got
Ka = Kp = 1
2. Calculate p1and p2 with L1 and L2 are known
3. Calculate the resultant of the area ACDE (P1) and z1 (the center of pressure for the area ACDE)
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64. CALCULATION STEPS ANCHORED SHEET PILE – FREE – CLAY
4. Calculate p6
5. Determination of penetration depth of sheet pile (D)
p6.D2 + 2.p6.D.(L1+L2-l1) – 2.P1.(L1+L2-l1-z1) = 0
6. Determination of anchor force
F = P1 – p6 . D
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65. CALCULATION STEPS ANCHORED SHEET PILE – FIXED – SANDJ
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66. CALCULATION STEPS ANCHORED SHEET PILE – FIXED – SAND
1. Determine the value of Ka and Kp
2. Calculate p1and p2 with L1 and L2 are known
3. Calculate L3
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67. CALCULATION STEPS ANCHORED SHEET PILE – FIXED – SAND
4. determine L5 from the following curve (L1 and L2 are known)
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68. CALCULATION STEPS ANCHORED SHEET PILE – FIXED – SAND
5. Calculate the span of the equivalent beam as l2 + L2 + L5 = L’
6. Calculate the total load of the span, W. This is the area of the pressure diagram between O’ and I
7. Calculate the maximum moment, Mmax, as WL’/8
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69. CALCULATION STEPS ANCHORED SHEET PILE – FIXED – SAND
(moment of area ACDJI about O’)
8. Calculate P’ by taking the moment about O’, or
9. Determine D
10. Calculate the anchor force per unit length, F, by taking the moment about l, or
(moment of area ACDJI about I)
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