The geological conditions of large underground cavern group are complicated

of which the support project affects stability of surrounding rock. So it is important to study the support optimization of large underground cavern group excavation. In order to simulate rock mass veritably and analyze its damage in construction

the elastoplastic damage model and damage evolution equation are presented on the basis of the irreversible thermodynamics theory. The 3D elastoplastic damage finite element code D-FEM is programmed by using Fortran language

which has the capabilities of simulating excavation and support

computing quickly and group function. 3D numerical model of underground cavern group is established

input initial geostress is inversion of field stress measurement. The cavern group excavation by different support projects is simulated by D-FEM. The stress

displacement and damage of surrounding rock under three different cases are analyzed. The effect of No.2 support project is best and so is proposed. Considering damage evolvement

damage zones compared to plastic zones of FLAC3D

damage zones in side wall of cavern group increase remarkably. So the elastoplastic damage finite elements can analyze stability of underground cavern engineering.