Design of Cantilever Retaining Walls in Unsaturated Soils Using AASHTO Load and Resistance Factor Design (LRFD) Method

摘要

Cantilever retaining walls have been the most common type of retaining walls. Proper drainage behind cantilever retaining walls is mostly provided and ground water table remains at or below the foundation subgrade during the wall design lifetime. Therefore, it is important to account for the unsaturated conditions of the retained soils in the wall design. AASHTO has recently adopted Load and Resistance Factor Design (LRFD) method for the design of retaining walls. In this paper, an external stability including sliding, overturning, and soil bearing for a typical reinforced concrete cantilever wall retaining unsaturated soils is evaluated using AASHTO LRFD method and incorporating the unsaturated soil mechanics theory in estimating the lateral earth pressures acting on the wall. The paper also shows that matric suction, an independent stress variable of unsaturated soils, is a source of resistance in the retaining wall design using AASHTO LRFD and results in more economic design.