Stability Analysis Of Surrounding Rock Of Underground Powerhouse On The Left Bank Of Wudongde Hydropower Station

The stability analysis of surrounding rock of underground chambers of hydropower stations is a complex nonlinear mechanical problem,which is usually accompanied by the characteristics of non-uniformity,discontinuity and large displacement of deformation.This article takes the underground powerhouse on the left bank of Wudongde hydropower station as an example,the deformation monitoring data of surrounding rock during construction period and within one year after excavation and support are analyzed.And based on the FLAC3 D software,the three-dimensional numerical model of the underground powerhouse on the left bank was established.Then the variation law of surrounding rock deformation,shear stress,minimum principal stress and maximum principal stress during the excavation and support of the underground powerhouse was calculated and analyzed by using finite difference method.The main research results are as follows:(1)Through the analysis of the deformation monitoring data of the surrounding rock of the top arch,rock-anchored beam and side wall during the construction excavation,the time-varying variation and spatial distribution of the surrounding rock deformation of different parts during the construction excavation are summarized.It is concluded that most of the deformation of surrounding rock in underground powerhouse shows continuous or step-like growth with construction excavation,and the deformation of a small part of surrounding rock does not increase significantly but stabilizes at a small value.(2)The variation and the rate of deformation during construction period and within one year after excavation and support of surrounding rock at different positions were analyzed.It is concluded that the monitoring data of deformation of the surrounding rock of the main plant has converged,and the deformation rate of the surrounding rock has also approached zero after the construction.The stability of the surrounding rock of the main plant is good.(3)Based on the FLAC3 D software,the three-dimensional numerical model of the underground powerhouse on the left bank of Wudongde hydropower station was established.The finite difference method was used to calculate the deformation and stress of the surrounding rock during the excavation and support of the underground powerhouse.The comparative analysis of the numerical calculation results and the actual monitoring results shows that the deformation law of the surrounding rock reflected by this two methods is similar.However,the magnitude of numerical calculation results is bigger than the actual monitoring results,and the difference is obviously in some positions.The difference may be related to the loss of monitoring data and the failure to consider concrete lining support during the numerical simulation.(4)The calculation results show that the deformation,shear stress,minimum principal stress and maximum principal stress of the surrounding rock of the main powerhouse are within a reasonable range during the excavation period.Although the maximum principal stress has a tensile stress,its magnitude is too small to influence the stability of the surrounding rock.The stability of the surrounding rock of the main plant is good.