Retaining Structures in Expansive Clays

Abstract

Under increasing moisture conditions, retaining structures in expansive clays experience swelling stresses. The magnitude of these stresses varies with the amount of water increase and the extent of soil confinement imposed by the retaining structures. This paper describes a comprehensive study of this problem for two types of retaining structures, namely drilled-shaft and tie back retaining walls. Its approach involves laboratory testing to characterize the swelling properties of the high plasticity clays encountered in South Texas and finite element simulation of the structural interaction between the soil and the retaining structures due to the moisture changes observed at an instrumented wall site. The magnitude of swelling pressures was found to decrease with depth following the diminishing increase in moisture with depth. The amount of soil confinement effected by the wall significantly increased clay swelling pressures.