Triaxial Test On Compression And Permeability Combined Mesoscopic Numerical Simulation Of Layered Rock Mass

The mechanical properties and permeability characteristics of layered rock mass under seepage environment play a key role in the design,construction and stability of layered rock mass.The factors of structural anisotropy,the coupling of stress field and seepage field make the seepage,deformation and stability analysis of layered rock mass become very complicated.In order to study the coherent evolution of stress-seepage in layered rock mass under osmotic pressure-stress coupling,triaxial test on compression and permeability was carried out on infilled sandstone and natural bedding sandstone with different structural plane angles,and the main research contents were as follows:For the infilled sandstone and natural bedding sandstone,the triaxial test on compression and permeability was carried out under the confining pressure of 20MPa,the osmotic pressure of 5 MPa and the confining pressure of 10 MPa,the osmotic pressures of 1 MPa,5 MPa and 9 MPa,and the stress-strain relationship,failure mode,permeability of the layered rock mass were obtained.The macroscopic experimental results preliminarily give the sensitivity analysis of the mechanical properties and permeability characteristics of the layered rock mass to the anisotropy and osmotic pressure of the structural plane,and provide data reference for the next step of numerical simulation.Based on the macroscopic experimental results,a discrete element PFC~2DD numerical model was established to meet the indoor test conditions,and the self-developed seepage-stress coupled biaxial compression program was used for simulation.The simulation work was carried out in two parts,namely,the numerical simulation of the compression and permeability test of the infilled sandstone and the numerical simulation of the compression and permeability test of the bedding sandstone.The numerical simulation of the compression and permeability test of the infilled sandstone studied the periodic characteristics of stress-strain characteristics,failure mode,initial permeability and permeability-strain curves in sandstone compression and infiltration process under different infilled joint angles,and explained the sandstone energy response mesoscopic analysis and energy transfer and dissipation law,and it discussed the influence of mesostructure on the seepage-stress coupling characteristics of infilled sandstones.The numerical simulation of the compression and permeability of the bedding sandstone focused on the stress-strain characteristics,strength deformation parameters,failure modes,contact force chain,displacement field and permeability evolution of different bedding angles,and analyzed the effect of osmotic pressure on the seepage-stress coupling characteristics during compression and infiltration.The mesoscopic simulation results show that the change of the mesostructure of the rock sample leads to the change of the seepage-stress coupling behavior of the layered rock mass.This study combines macroscopic research and mesoscopic research,and it complement each other,deepening the study of compression and permeability mechanical behavior of layered rock mass under osmotic pressure-stress coupling conditions.