Abstract:With the developing of hydroelectricity resource

more and more hydropower stations were built in alpine valleys which had complex geographic and geomorphic conditions

and many of them were built in underground with bedded rock.Therefore it has been a critical issue to quantitatively analyze the deformation and stability of underground powerhouse located in bedded rock.The deformation of bedded rock with different dense was analyzed in this case by means of field monitoring and numerical simulation.The results of deformation monitoring

acoustic wave testing and microseismic monitoring were employed to reveal the deformation law and damage zone of surrounding rock.Based on the characteristics of geologic framework and measured data

a calculation model was established to study the stress and deformation field

and plastic zone for the purpose of searching for the potential damage zone of the underground powerhouse during excavation unloading by using the plastic zone had a close connection with that of deformation.The difference of deformation was the result of discrete element analysis procedure UDEC.It was shown by the simulation and microseismic monitoring toghther that when the 6th floor which is between the elevation 815~809 m

the deformation value of elevation 812 m at the upstream side wall increases the fastest

and the amount of maicroseismic events around it increased rapidly.As a whole

the unloading of X axis was more acute than that of Y axis;the defomation value of the upstream side was greater than that of the downstream side.The maximum value of the deformation appears at the elevation of 812 m at the upstream side wall where the value of deepness of the plastic zone is largest.The distribution was more intensive bedding joint at the upstream side than that of the downstream side. The deformation of the surrounding rock has a close connection with the dense of the bedding joint

and the excavation will lead to the activity of bedding joint

leading to the damage of the surrounding rock and reducing the overall strength of the surrounding rock.The severer the excavation is

the faster the quantity of microseismic event increases.The research results will provide useful references for later construction and operation of the underground powerhouse.