Modelling Drilling and Settlement of Helical Pile Using Mohr-Coulomb (VUMA) Based on Stress Return Criteria.

Conventional Mohr Coulomb model is non-trivial to implement in the finite-element method due to the fact that the Mohr-Coulomb yield criterion and the corresponding plastic potential possess corner sand an apex, which causes numerical difficulties. Mohr coulomb is limit function plot as a non-uniform hexagonal cone in a plane stress strain. The Mohr coulomb yield function has a corner which may cause difficulties while may cause difficult in the modelling complex finite element analysis scenario. ABAQUS built in model uses a rounded version of plastic material which may not run stable for perfectly elastic material. In this model stress update criteria is used with small modification to the formulation of constitutive matrix on corner and apex is performed. A 3d helical pile installation and settlement in performed in a sandy soil with negligible cohesion, and the results shows that resultant settlement is a key function of cohesion as well as loading rate.