Creep Damage Characteristics And Stability Control Of Rock Mass Under Seepage Fissure Coupling

Deep soft rocks are mostly heterogeneous rock mass with joints and fissures,and often have long-term properties such as high in-situ stress,high Mpa and strong mining disturbance.Under the influence of multiple factors,deep engineering soft rocks are prone to deformation,which leads to deformation and instability of surrounding rocks and failure of supporting structures.Moreover,the deformation and failure mechanisms of soft rocks under various coupling fields remain unclear and are difficult to predict and effectively control.Therefore,this study investigates the evolution law of mechanical behaviors of fractured rock mass under the coupling action of high stress field and seepage field,determining the stress conditions for initiating and accelerating the creep deformation and instability of rock mass and revealing the aging deformation and meso-instability mechanism of surrounding rocks in deep rock engineering.The research results will be of extremely important scientific research value and have broad engineering application prospects,providing significant engineering guidance for the reinforcement design of surrounding rocks,disaster prevention,and safe production of ultra-deep mine engineering.With the support of the National Natural Science Foundation of China?51774166?,this study conducts the conventional triaxial test of sandstone,model test of similar materials,and GDS creep test of soft rocks to explore the laws of mechanical property deterioration and creep damage of sandstone.Based on similarity criterion theory and uniform similarity theory,the parameters and models of similar material for single-fracture sandstone are determined.A statistical damage constitutive model of sandstone and a new fractional damage-creep constitutive model considering time scale effect are established by jointly drawing on the theory of continuum damage mechanics,strain equivalent principle and fractional calculus principle.The main research results are as follows:?1?The stress-strain curves of sandstone are obtained by carrying out tests of examining mechanical properties of sandstone under different conditions,thus determining the basic physical mechanical parameters of sandstone and the damage evolution law of mechanical properties of sandstone.?2?Through model tests of similar materials,the similar material types and fitting proportion parameters close to the original sandstone are obtained,and the parameters and models of single fracture specimens are determined.?3?The creep test of single-fissure sandstone specimens under seepage is carried out.The creep curves are obtained and the sensitivity of fracture parameters in the creep test is analyzed.Based on the damage mechanics theory,a new fractional damage-creep constitutive model considering time scale effect is established,numerically solved and verified.?4?Based on the creep constitutive model and FLAC^3D software,numerical simulation is carried out to analyze the failure law of surrounding rock s and supporting structures of deep ingate cavern.The numerical results are compared with the stress of supporting structures of the ingate cavern and the actual damaged area of supporting structures in situ.The above research results elaborate the laws of the mechanical property damage and the aging creep deformation of sandstone in principle,providing scientific reference for structural stability of deep underground mining as well as theoretical and applied basis for enriching and expanding the creep law of soft rocks.