LATERAL EARTH PRESSURE. GENERAL Lateral earth pressure represents pressures that are “to the side” (horizontal) rather than vertical. Caused by soil self.

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1 LATERAL EARTH PRESSURE

2 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

3 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.

4 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.

5 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.

6 AT REST EARTH PRESSURE q vv hh z  v = . z + q At rest, K = K o Jaky, Broker and Ireland  Ko = M – sin  ’ Sand, normally consolidated clay  M = 1 Clay with OCR > 2  M = 0.95 Sherif and Ishibashi  K o = +  (OCR – 1) = 0.54 + 0.00444 (LL – 20)  = 0.09 + 0.00111 (LL – 20) LL > 110%  = 1.0 ;  = 0.19 Broker and Ireland K o = 0.40 + 0.007 PI, 0  PI  40 K o = 0.64 + 0.001 PI, 40  PI  80

7 ACTIVE EARTH PRESSURE

8 RANKINE ACTIVE EARTH PRESSURE Ka = tan 2 (45 -  /2)  1 =  3. tan 2 (45+  /2)+2c.tan (45+  /2)  a =  v. tan 2 (45-  /2) – 2c. tan (45-  /2)  a =  v. Ka – 2c  Ka

9 RANKINE ACTIVE EARTH PRESSURE (INCLINED BACKFILL) (for granular soil, c = 0) For c-  soil

10 COULOMB ACTIVE EARTH PRESSURE Assumptions: -Fill material is granular soil - Friction of wall and fill material is considered - Soil failure shape is plane (BC 1, BC 2 …) Pa = ½ Ka. . H 2

11 COULOMB ACTIVE EARTH PRESSURE (SURCHARGE ON BACKFILL)

12 RANKINE PASSIVE EARTH PRESSURE

13  p =  v. tan 2 (45+  /2) + 2c. tan (45+  /2)

14 RANKINE PASSIVE EARTH PRESSURE Kp = tan 2 (45 +  /2)  h =  v. Kp + 2c  Kp

15 COULOMB PASSIVE EARTH PRESSURE Pp = ½ Kp. . H 2

16 LATERAL EARTH PRESSURE DUE TO SURCHARGE a > 0,4 a  0,4

17 LATERAL EARTH PRESSURE DUE TO SURCHARGE

18 PURPOSE OF LATERAL EARTH PRESSURE STABILITY ANALYSIS GRAVITY WALL AGAINST SLIDING OVERTURNING

19 PURPOSE OF LATERAL EARTH PRESSURE

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