水平地震力作用下岩体破坏机理探究

Research on the Failure Mechanisms of Rock Masses under Level Seismic Loading

基于摩尔库伦强度准则和波动理论对地震作用下岩体的破坏机理进行研究。结果表明:当埋深在一定范围内,水平地震作用下岩体的内聚力c和正应力σn与振动速度和埋深呈线性关系。当埋深一定时,振动速度越大c值越小;在振动速度增大的过程中岩体的应力状态由压应力逐渐转变为拉应力,且拉应力随振动速度的增大而增大;当振动速度一定时,岩体埋深越大c值越小;埋深越浅,拉应力越大,当埋深达到一定值时岩体就只在其弹性极限内振动而不产生破坏。

Based on Mohr-Coulomb failure criterion and wave theory,the failure mechanism of rock and soil masses under earthquake loading has been theoretically analyzed,with the calculation process assuming the maximum value of seismic stress and the most unfavorable orientation.It has been found that cohesive force and normal stress are linearly related to vibration velocity when the burial depth is within a certain range.When the burial depth is constant,vibration velocity increases as cohesive force,c,decreases,so with increasing vibration velocity,stresses in the rock mass would transform from the compressive state to the tensile state and continue to increase.When the vibration velocity is constant,the deeper the burial depth of the rock mass,the smaller is the cohesive force;and the shallower the burial depth,the greater is the tensile stress.When the burial depth increases to a certain value,the rock mass begins to vibrate within the elastic limit and no failure can occur.This research can be applied to the assessment of rock mass stability and the forecasting of geological hazards,as rock masses under different burial depths always have different stress states.More specifically,rock masses buried shallowly store only a small amount of strain energy,limiting their destructive potential.Increasing the burial depth correspondingly increases the strain energy;as a result,the rock masses are closer to reaching their limit state and can more easily fail.The evolution of geological bodies shares a similar rule;namely,when a geological body reaches its limit state,a slight perturbation can trigger a geological hazard,whereas if the geological body has not yet approached its limit state,only a sufficiently strong disturbance will induce the geological hazard.