Undrained horizontal-moment bearing capacity of caisson foundations in over-consolidated clay considering effects of gap

Abstract

When a caisson foundation moves laterally, a gap between the rear side of caisson and the soil is more easily formed in over-consolidated clay. The undrained horizontal-moment bearing capacity of a caisson foundation in over-consolidated clay was investigated through 3 D finite element analyses. To investigate the effects of aspect ratio, caisson size, surface soil strength, and soil strength distribution on gap formation, a parametric study was conducted for L/D ratios varying from 0.5 to 3, diameters varying from 4 m to 12 m, lengths varying from 6 m to 24 m,s_um varying from 2 kPa to 20 kPa and k varying from 0 to 1.5 kPa/m. The results show that the failure mode of caisson foundation under lateral load and moment in over-consolidated clay changes due to the formation of a gap. The gap has a significant impact on the undrained bearing capacity of caisson foundations, and with the decrease of caisson size or the increase of surface soil strength, the gap has a greater impact on the bearing capacity. Based on the research, a gap-influence coefficient and horizontal-moment composite bearing capacity has been summarized to provide reference for the design of caisson foundation in over-consolidated clay.

Keywords:

• H-M composite bearing capacity
• gap effects
• three-dimensional FEM
• caisson foundation

Disclosure statement

No potential conflict of interest was reported by the authors.

Additional information

Funding

This work was supported by the National Natural Science Foundation of China under Grant 41672272 and 41427803; and Primary Research and Development Plan of Shandong Province under Grant 2017GGX30125.