The Nonlinear Energy Analysis Of Surrounding Rocks In Deeply Buried Cavity With Concealed Karst Cave On The Top

In the western region with rugged terrain,tunnels are used to overcome elevation barriers,when building railways or highways.However,there are still some problems,and it is common to have karst caves around the plan chamber.When the cave is above the axis of the chamber,the surrounding rock is prone to collapse.Therefore,this article bases on the generalized HoekBrown failure criterion and the limit analysis theory,to study the collapse failure mode of the surrounding rocks of the deep-buried chamber with caves on the top.The main research content is as follows:(1)According to the collapse characteristics of the surrounding rocks induced by the top cave,there are the failure mechanism of cavern surrounding rock collapse induced by the top cave.The internal energy dissipation power and external power are obtained by the upper limit theorem.the equation of the collapse curve of the surrounding rock at the top of the chamber is calculated by variation.(2)In calculation,the definition of the limit excavation span of the chamber is given,and the analytical solution of the limit excavation span of the chamber is obtained by Virtual work principle.Therefore,the influence of the limit excavation span of different parameters is analyzed,and the influence law of different parameters on the excavation span of the chamber is summarized.(3)The collapse failure mechanism of the surrounding rock at the top of the chamber is constructed by the difference in the physical and mechanical characteristics of the upper and lower strata in the heterogeneous strata.The limit excavation span of the chamber and the collapse range of the top surrounding rock under different parameter differentiation levels are obtained by calculations.Therefore,the influence of changes in surrounding rock parameters of each layer of the rock mass on the limit excavation span of the chamber are found.(4)Relying on project,the collapse process of surrounding rock on the top of the chamber is simulated,and the numerical solution of the collapse failure curve of the surrounding rock is obtained.The validity of the theoretical analysis is verified by comparison.