Research On Underground Caverns Adjacent Stabilization Under Different Yield Condition

With the restriction of land form and influence with other factors, factory building was often demanded to lay out underground in the process of building large-sized hydraulic engineering in the west of China. The study on stabilization of underground engineering has become major study nowadays. The stability condition of underground cavern adjacent rock is greatly affected by the adjacent rock stress condition.In this paper, WuJiangSiLin engineering was studied. Its underground factory building initial ground stress field, adjacent rock stabilization and excavation subsequence were studied by using the method of nonlinear finite element analysis, based on different forms of selecting yield criterion. The method and content of the paper are as follows:(1) The genesis and influencing factor of initial ground stress field was analysed and induced. Five group of ground stress test was made in the underground factory building of WuJiangSiLin hydropower station. Then azimuth of maximum principal stress in the underground factory building was found by using the regression analysis which analysed ground stress field.(2) Based on expounding rock mass yield criterion and nonlinear theory , yield criterion used by numeric analysis of some China hydropower station underground factory building was analysed and induced .With the analysis of WuJiangSiLin engineering by using the method of nonlinear finite element analysis, the proper yield criterion was accessed.(3) Carried out generalized Mises yield criterion , yield curve on the n flat face was circle curve, and different elected parameters correspond to external angular point circumcircle, internal angular point circumcircle and incircle of Mohr-Coulomb unequiangular hexagon. According to unequiangular hexagon, circle yield curve which had the same area as hexagon can be found, and corresponding yield criterionwas equilateral circle yield curve. Based on elemental material parameter c and φand corresponding parameter α and κ of different yield curve, the analysis of underground cavern adjacent stabilization was carried out by using the method of nonlinear finite element analysis.(4) Based on the method of this paper , the finite element calculation of WuJiangSiLin hydropower station underground caverns was carried out. Because of different yield curve, the effect on underground factory building adjacent rock displacement , stress and plastic zone dimension was contrasted.