A análise elasto-plástica de túneis pelo método dos elementos finitos

Abstract

In this paper a finite element program for the elastoplastic plane strain analysis was developed. Its purpose is to compute the displacements and stresses in soil and rock masses, and in tunnel supporting elements. Basic characteristics of other tunnel design methods have also been discussed. At the sarne time, emphasis was given to the study of plasticity concepts and stress-strain behavior of soils. Drucker-Prager's model has been chosen to simulate the inelastic behavior of the medium. In the finite element analysis the isoparametric quadratic displacement method was used. In order to reproduce the physical non-linearity, the "initial stress" method (incremental and iterative) was applied. The program permits to analyse each step of excavation according to the construction methods. In order to show the validity of both the elasto-plastic model and the simulation process used, the program was applied to typical tunnel cross-sections. Since reasonable results were obtained the program will be seemingly useful in tunnel design. The program could also be used in other geotechnical problems where the plane strain condition is valid.