Stability Analysis of Surrounding Rock of Underground Powerhouse during Excavations at Stages in High Geostress Region

According to the geological environment of underground powerhouse,an inversion analysis for the initial geostress filed is carried out and it is concluded that the region is belong to middle-high terrestrial stress.Based on the layout and excavation sequence of underground powerhouse,the whole three-dimensional computational model is established by using FLAC3D software.And then the distribution rules of stress filed,displacement field and yield zones around main caverns are analyzed during the process of excavation at stages.The results show that the given excavation sequence and anchored parameters are effective in limiting development of damage zones and deformation of surrounding rock,and improve stress state of surrounding rock;but the condition of surrounding rock is week relatively to high geostress filed so that the disturbance in deep excavation is difficult to control.It is recommended that additional supports should be strengthened in local positions.