Study On Three-dimensional Dynamic Stability Of Surrounding Rock At The Top Of Rectangular Chamber

The safety assessment of underground chamber stability under seismic effect and the determination of potential failure surface of surrounding rock under the limit state of underground chamber are the research hotspots of underground space engineering at the present stage.Therefore,earthquake is a very destructive natural disaster,especially in underground space engineering,rock and soil structure is easily affected by earthquake disturbance,easily cause collapse accidents and casualties.In this paper,relying on the National Natural Science Foundation of China(52074116,51804113,52004088),based on the maneuvering the upper bound limit method and H-B nonlinear failure criterion,combined with the reliability theory of variational method and numerical method,the three-dimensional dynamic stability of surrounding rock at the top of rectangular underground chamber was studied.The main contents and conclusions are as follows:(1)According to the upper bound limit method and the H-B nonlinear strength criterion,the pseudo-static method was introduced to the earthquake force.The three-dimensional dynamic stability analysis model of surrounding rock at the top of rectangular chamber was established.Based on the principle of virtual power,at the top of the rock mass of underground cavern limit state equation was deduced.The three-dimensional underground cavern under critical state collapsing the objective function was solved by the variational method.The potential collapse range and height of the top of rectangular chamber are obtained.In addition,the anchor was introduced into the calculation model,this paper the analytical solutions of prestressing force of cable-anchors was derived.By using Matlab in the sequential quadratic programming(SQP)algorithm,the upper limit of the optimal solution of cable-anchors pre-tightening force was solved.The influence of H-B criterion of seismic force and support strength on collapse range and anchor cable preload of rectangular chamber was studied.(2)Anchor rope support under rectangular cavern reliability model was built.The failure probability and reliability index of underground cavern was solved by using the response surface method(RSM).The method of support for the earthquake effect under rectangular cavern system reliability evaluation was provided.The seismic force H-B guidelines and support strength parameters such as impact on the reliability of the rectangular cavern under earthquake effect was analyzed.(3)To actual engineering as the background,the transportation alleys stability under the original support scheme was analysed by using the theory method.The transportation lane at the top of the wall rock cave range and potential height was sloved.The original support parameters were optimized,and the rationality of the optimized parameters and the feasibility of the research method were verified by combining the numerical simulation and field monitoring results.