Stability analysis of underground houses in Xiaowan hydropower station by finite element method, a case study

In this study, the geological setting of the Xiaowan hydropower station project is introduced and finite element model for the underground structures is presented. Sequential excavation of the underground structures is simulated by finite element method (FEM) in which elasto-perfectly plastic (EP) and elastic-brittle-plastic (EBP) constitutive models are applied to carry out the analysis. Efforts are made to evaluate the influence of the two constitutive models on the deformation and damage zone of the rock mass surrounding the underground structure. Numerical results show that both deformation and the damage zone after the excavation completion of the underground structures are larger in EBP model than those in EP model under the same conditions. This indicates that the EP model may overestimate the stability of the structure. Meanwhile, the characteristic of the deformation and damage zone, especially the influence of faults on them, is analysed.