Study on bearing characteristics of rigid rectangular foundation subjected to horizontal force and torque (H-T)

The current design of member foundation only considers horizontal forces (H) and ignores the effect of torque (T), which may lead to torsional failure of the foundation. To analyze the bearing characteristics of rigid rectangular foundation subjected to horizontal force and torque (H-T), according to the stress characteristics of the foundation, the corresponding simplified calculation model is established, and the theoretical solutions of the stress and deformation analysis of the foundation under the two bearing modes of torque (T), horizontal force (H) - eccentric bending moment (M) are derived; numerical simulation analysis is carried out to obtain the failure envelope of rigid rectangular foundations under push torsion H-T load. And then the rationality of the theoretical calculation method is verified by the indoor model test. Finally, the influences of torsion ratio and foundation resistance ratio coefficient m on the stress and deformation of foundation are analyzed. The results show that the failure envelope of rigid rectangular foundation under push torsion H-T load is approximately parabolic. With the increase of torsion-thrust ratio, the horizontal bearing capacity of the foundation decreases, and its failure mode changes from horizontal deformation failure to torsional deformation failure. The increase of the proportional coefficient m can reduce the horizontal displacement and rotation angle at the foundation ground effectively. To ensure the safety and stability of the rigid rectangular foundation, the nature and compaction of the overlying backfill should satisfy the design requirements. This study can provide basic information for the design of multi-rod unified rod foundations.