A major problem engineers face in the analysis of excavation by the classical methods is the difficulty of predicting displacements around the support structure. To solve this problem, finite element method (FEM) is increasingly employed. However, so many engineers in the field have little knowledge of FEM that hampered the method to spread in practice.

In this paper authors attempt to provide a useful tool for field engineer, who know little of FEM, to design the structure by both classical pressure diagram and FEM methods at same time. At first, calculate depth of pile and anchor force by each of classical methods, including free earth support, fixed earth support, a modified and an improved fixed earth support, and then compute the displacements by FEM method for each situation respectively. For FEM method, an elasto-plastic theory and a Mohr-Coulomb constitutive law are adopted for soils and the mesh is automatically formed. After comparison, a safer and more economical design can be selected. To support this method, a computer package on Windows 95 base has been developed by the authors. Results of a practical example show that the improvement of fixed earth support method is better for the design.