The Research For Surrounding Rock Stability Of Excavation Based On Deep Underground Laboratory In Beishan

There are joints,fractures in the rock mass,making the rock mass an incomplete continuum.The structural planes and weak interlayers,which are criss-crossed inside the rock mass,pose difficulties for underground construction.In order to accurately evaluate the stability of surrounding rock in deep roadway,it is an indispensable step to study the mechanical behavior of rock mass.In terms of geotechnical computation,the Discrete Element Method can more realistically characterize the geometric features of jointed rock masses,and can obtain practical numerical simulation results for rock mass failure problems concentrated on joint surfaces.Therefore,the discrete element method has been widely used in solving rock mechanics problems such as slope,dangerous rock and roadway stability.This paper is based on underground laboratory for disposal of high-level radioactive waste.According to the indoor rock mechanics test,combined with the existing theoretical classification method,a system for evaluating rock mass quality is used to obtain rock mass parameters for actual engineering.Further study on the stability of roadway surrounding rock by DEM.The research work and results of this paper are as follows:Through the conventional rock triaxial test,obtained the physical and mechanical parameters of intact rock,and research the mechanical properties of the rock mass under different confining pressures.According to the RMR,GSI and other rock mass classification methods proposed by the predecessors,a system for evaluating the quality of engineering rock mass is established,and the mechanical parameters corresponding to the actual rock mass are obtained.The selection of different strength criterion may have an impact on the calculated rock mass deformation and damage.This paper selects the Mohr-Coulomb and Hoek-Brown strength criteria for comparison.Simulate the compression test of different strength specimens under different confining pressures,analyze the stress-strain curves of the specimens using two strength criterion,compare the Mohr-Coulomb and Hoek-Brown strength criterion to describe the differences in mechanical behavior of rock masses,and select strength criterion applicable to model calculations.A series single structural plane and roadway model was established to analyze the deformation and stress field distribution of the surrounding rock under different structural plane.It can be found from the calculation results that the displacement amount is the largest when the structural plane penetrates the center of the roadway;if the structural surface is biased toward the side of the roadway,the maximum displacement direction is normalized to the structural surface.If the structural plane and the roadway are in an oblique state,a slide occurs between the roadways on both sides of the structural surface.Significant stress concentrations occur at the intersection.In order to study the interaction between roadways,this paper establishes three different combinations of double roadway models.In the parallel roadway model,as the spacing between the roadways is shortened,the displacement field at the top of the roadway is affected by the adjacent roadway and gradually moves toward the middle.When the two roadways intersect,significant deformation and stress concentration areas appear at the intersections.Underground laboratory for disposal of high-level radioactive waste is a group of caverns composed of multiple sizes of roadway intersections.Based on the conclusions obtained from the simple roadway model,this paper studies the effect of excavation of deep cavern group on the overall structural stability.The expansion of the plastic zone around the cavern group under different rock mass strengths is analyzed,which provides a reference for underground engineering construction under different geological environments.In this paper,the rock mass parameters are obtained through rock mechanics test and rock mass quality evaluation system,and the differences between the two strength criterion in the application of DEM are compared.The effects of structural plane,roadway excavation and rock mass on the displacement and stress fields of surrounding rock in deep roadway are analyzed.