KA and Ko Behind Rotating and Non‐Yielding Walls

Abstract

This paper reports on the magnitudes and distribution of static at‐rest stresses behind a rigid wall as a function of soil densification and on static active stresses mobilized behind a rigid wall rotating about its base. The experiments were conducted on the retaining wall system which is permanently affixed to the University of Washington shaking table which is described. Based on these experiments on Ottawa sand, the following conclusions are drawn: (1) The stress distribution behind a non‐yielding rigid wall is hydrostatic; (2) the well known Jaky equation applies only when the backfill is deposited at its loosest state; and (3) when the backfill behind the wall is either compacted or vibrated to increase its density, the magnitude of the at‐rest stresses increases due to densification and the total at‐rest stress exerted on the wall will then be the sum of the stresses due to gravity effects and the locked‐in horizontal stresses due to densification. For a rigid wall rotating about the base: (1) The static active stress distribution behind the wall is also hydrostatic; (2) soil densification de creases the magnitudes of active stresses behind such walls; (3) the magnitude of the active stresses behind a wall rotating at its base can be obtained by the classical Coulomb equation; and (4) the state of active stress propagates down ward from the surface of the soil with increasing wall rotation.