Experimental and analytical study on the bearing capacity of caisson foundation subjected to V-H combined load

In geotechnical engineering, the bearing capacity of caisson foundation subjected to combined vertical and horizontal (V-H) load is of significant concern. This study performed laboratory model tests to explore the mechanical response of caisson foundation with different embedment ratios under various load combinations. The caisson foundation was instrumented with displacement transducers to collect the load-displacement (p-triangle s) behaviors of the foundation and the soil displacement (p-u) around the foundation. The progressive failure mechanism was revealed by visualized semi-model test combined with Digital Image Correlation (DIC) technique. Test results show that the ultimate bearing capacity of the foundation increases with the embedment ratio of the foundation and vertical load. The failure envelope of the shear zone exhibits a semi-general shear failure which differs with embedment ratio lambda. Based on the failure modes and soil displacement vector, the soil failure maneuvering field was established. Then, the analytical expression of bearing capacity considering the coupling effect of V-H load was proposed based on the upper limit theorem. The analytical solution was further assessed by comparing with the test results.