1. 2. 3. 4. S. 6. 7. The coefficient of earth pressure at rest for overconsolidated clays is greater than for normally c

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1 2 3 4 S 6 7 The Coefficient Of Earth Pressure At Rest For Overconsolidated Clays Is Greater Than For Normally C 1 (60.35 KiB) Viewed 9 times

1. 2. 3. 4. S. 6. 7. The coefficient of earth pressure at rest for overconsolidated clays is greater than for normally consolidated clays. Jaky's equation for lateral earth pressure coefficient at rest gives good results when the backfill is loose sand. However, for a dense sand, it may grossly underestimate the lateral carth pressure at rest. For Rankine's theory, it is assumed that the wall is frictionless and extends to an infinite depth. If the wall gradually is pushed into the soil mass up to the failure of the soil occurs, this situation is referred to as active state. If the wall is allowed to move away from the soil mass gradually, the horizontal principal stress will decrease. The state of plastic equilibrium and failure of the soil will occur. This situation represents Rankine's passive state For Rankine's passive state, the failure planes in the soil make +(45 - ' 2) degree angles with the horizontal plane. Coulomb's carth-pressure theory for a cohesionless backfill assumed that the failure surface is a plane. The wall friction was not taken into consideration For retaining walls with backfill sloping at an angle with the horizontal, the directions of Rankines active or passive pressures are no longer horizontal. Rather, they are inclined at the same angle with the horizontal For calculation of the total active force, common practice is to take the tensile cracks into account. Because no contact exists between the soil and the wall up to a certain depth after the development of tensile cracks, For a frictionless wall with the vertical back face supporting a horizontal granular soil backfill, Coulomb's active and passive carth-pressure coefficients become the same as Rankine's active and passive earth-pressure coefficients. Active earth pressure coefficient values are smaller than passive earth pressure coefficient values. For given value of ', the value of K, decreases with increasing the wall friction. For a given value of the effect of wall friction is to reduce somewhat the Coulomb's active earth pressure coefficient. Earth pressure coefficient at-rest is greater than active earth pressure coefficient and smaller than passive earth pressure coefficient 8. 9. 10. 11. 12 13. . 14.