 
Summary: PARALLEL COMPUTING OF UNSATURATED SOILS USING ELEMENTBYELEMENT
AND DOMAIN DEOMPOSITON METHODS
Youliang Zhang, Domenico Gallipoli & Charles Augarde
School of Engineering, Durham University, U.K.
Abstract: The finite element (FE) simulation of large scale boundary value problems in unsaturated soils is
particularly timeconsuming owing to the complex properties of the unsaturated porous media. To speed up
analyses, a parallel FE code has been developed in this work by using C++ and MPI running on a Linux
parallel computer cluster. The "Divide and Conquer" strategy has been used to partition the task among the
processors with minimum data exchanges and load balancing. The linear system of equations was solved
using the iterative solver BiCGSTAB incorporated within an elementbyelement method. One serial and one
parallel calculation are presented to validate the code and to test the parallel performance the algorithm.
1. INTRODUCTION
Understanding the behaviour of unsaturated
soils is important for many geotechnical
applications in natural soil deposits (where the
water table is at some depth below ground surface)
as well as in compacted soils used as fill material.
The accurate analysis of unsaturated soils by the
finite element methods requires consideration of
the physical coupling among three phases, i.e. the
