深埋隧洞TBM施工过程应变型岩爆能量演化规律及影响因素OA

To reveal the energy evolution laws and influencing factors of strain rockbursts induced by TBM excavation in deep tunnels,firstly,a 3-D refined numerical simulation of TBM tunneling and support for a granite rockburst section of an actual engineering project was conducted by using an internal variable creep model.Secondly,the evolution pattern of strain energy density and energy dissipation rate of surrounding rock during TBM construction process were analyzed,with its rationality verified against actual rockburst cases.Finally,the influences of rock properties,in-situ stress,and TBM advance rate on energy evolution were investigated.The results show that the energy evolution during strain rockburst formation process exhibits double-peak characteristics,corresponding to instantaneous rockbursts near the tunnel face and delayed rockbursts occurring at a certain distance behind the face,respectively.The field-observed moderate rockburst manifests typical delayed strainburst features like rock slab buckling and rock fragment ejection.The secondary concentration zones of numerically calculated strain energy density and energy dissipation rate show good agreement with the actual rockburst region(8-14 m behind the face and 30°-60° on the left side of tunnel invert).Strain energy density can indicate the severity of rockburst hazard(energy storage scale),while energy dissipation rate,as a stability indicator,can evaluate rockburst tendency(potential instability locations).Their combination offers a promising approach for comprehensive rockburst risk assessment.Increasing strength parameters a and R raises the strain energy peak but lowers the energy dissipation rate peak,whereas the effect of increasing viscosity coefficient κp2(controlling steady-state creep rate)is opposite.Increasing viscosity coefficient ηp1(controlling transient creep rate)primarily enhances the spatial lag of energy peaks.When the lateral pressure coefficient of minimum horizontal principal stress increases from 0.8 to 1.6,the rockburst risk intensifies markedly,and the strain energy and energy dissipation rate peaks of surrounding rock increase by approximately onefold and twofold,respectively.An increase in the TBM advance rate primarily leads to a rise in the peak energy dissipation rate.When the rate exceeds a certain threshold range,rockburst tendency can increase significantly.