NUMERICAL ANALYSIS OF ULTIMATE BEARING CAPACITY OF LARGE-DIAMETER CYLINDRICAL STRUCTURES DEEPLY EMBEDDED IN CROSS-ISOTROPIC SOFT SOIL AGAINST LATERAL LOADS
Abstract：A modified three-dimensional plastic limit analysis method of bearing capacity of large-diameter cylindrical structure in cross-isotropic soft ground is presented. The most likely failure mechanism is assumed to be of a composite rupture surface which is composed of an individual wedge in passive zone or two wedges in both active and passive zones near the mudline，depending on separation or bonding state at the interface between the cylindrical structure and neighboring soils in the active wedge，and a truncated spherical slip surface at the base of the cylinder when the structure tends to overturn around a point which is located on the symmetry axis of the structure. The cylindrical structure and soil interaction system under consideration is also numerically analyzed by the finite element method with software ABAQUS，in which the soil is assumed to obey the Hill¢s yield criterion. Both the failure mechanism assumed and the plastic limit analysis predictions are validated by numerical computations based on FEM. The effects of strength anisotropy of soil，height of loading action point above the mudline and coefficient of friction of the soil-structure interface on bearing capacity of deeply-embedded large-diameter cylindrical structure are examined through comparative analyses.
