Undrained Stress Distribution by Numerical Methods

Abstract

Stress distribution in incompressible or undrained soil is important to the engineer, but the usual finite difference and finite element methods break down for incompressible materials. A revised procedure is described in which the pore pressure is treated as another unknown. Specific application is made to linearly elastic materials; however, the technique can be used for other stress-strain relations. The paper shows the form of the procedure used for finite elements, and that used for a lumped parameter model equivalent to a finite difference method. Results for a sample problem illustrate the insensitivity of vertical stress to compressibility and show the larger effects on the other stress components. Comparison of undrained and drained analysis shows the motion of soil towards the load during consolidation.