Comparative Study of FLAC3D Strain softening model and Mohr-Columb model On Engineering Application

• 1、School Of Civil Engineering And Architecture,East China Jiaotong University,Nanchang 330013

Abstract：To evaluate strain-softening phenomena of surrounding rock during the excavation accurately, and search the composition model that could be used in numerical analysis of deep eengineering appropriately, proceeded the study as follows: firstly, according to incremental theory, deduced the expression of plastic parameter of strain-softening model. secondly, through a series of uniaxial numerical loading example of rock，the stress-strain numerical results of Mohr-Coulomb elastoplastic model and strain-softening model are analyzed. Thirdly, the strain-softening model is used to the deep underground tunnel of Xiaoguanzhuang; mainly for the analysis of thesurrounding deformation, plastic zone and factor of safety, and the stability of underground caverns is evaluated. Based on the In line fish language of FLAC3D, the program of safety factor with Mohr-Coulomb criterion is compiled. The computed result indicated that , compared with Mohr-Coulomb elastoplastic model, strain-softening model would achieve larger displacement , more plastic zones ,lesser safety factor . Tunnel excavationwould cause a larger range of disturbed area, result of strain-softening model is closer to the actual result. Conclusion：Mohr-Coulomb elastoplastic model could not reflect strain-softening phenomena of surrounding rock effectively, strain-softening model is more suitable in numerical simulation of deep engineering.)

Keywords： deep tunnel surrounding rock softening numerical analysis safety factor