Role of Torsional Shear in Combined Loading of Drilled Shaft Foundations

摘要

Deep foundations may be subjected to combined torsional and lateral loads. However, there are few full-scale observations to inform a complete understanding of the possible foundation response. This paper describes the generation and transfer of lateral loads that developed within drilled shaft foundations subjected to quasi-static and cyclic torsional loads. Due to differences in stratigraphy, one drilled shaft experienced geotechnical torsional failure, whereas the other did not. Torsional loading to failure produced shear cracks that softened the soil-structure interface and produced a softened response to the lateral load that developed. Cyclic loading resulted in increased lateral displacement at near-constant lateral load amplitude. The maximum bending moment observed in the shaft that experienced torsional failure was significantly greater than that in the shaft in which geotechnical failure did not occur, and greater than that anticipated from lateral loading alone.