2-D Stress-Stratin Analysis for Underground Excavations in Rock With Non-linear Elasto-Plastic Behavior Using FEM (Finite Element Method)

In this research, two-dimensional analysis is applied to surrounding underground excavations that behave in nonlinear elasto-plastic manner. A computer program (FEP: Finite Element Program) was developed based on finite element method. The main output of applying the FEP is the calculation of the value of stress and strain in elasto-plastic conditions. The principles of FEM in stress analysis are first described, then the principles of solid mechanics explained, and consequently the final formulas of finite element analysis are derived. Main formulas of plasticity are defined and then combined with elastic formulas to acquire the FEM elasto-plastic formulas. The details of subroutines can be found after the theoretical discussion. Finally, the ability of software was examined by execution of the FEP with theoretical and practical examples. A good agreement is observed when the FEP is compared with other program (Ansys) and empirical methods. Criteria definition of rock mechanics is the main advantage of the FEP with respect to other softwares.