Failure Mechanism Of High Rock Slope In Alpine Region Considering Time Effect

With the implementation of the western development strategy,Qinghai Tibet railway and other major projects,the number of construction projects in cold regions is increasing,and the problem of frost damage in cold regions is becoming increasingly prominent.In this paper,the mechanical characteristics of freeze-thaw damage of rock mass and the failure mechanism of rock slope are studied.The failure mechanism of rock slope in cold region is studied by laboratory test,theoretical model,numerical simulation and other research methods.The main research contents and conclusions are as follows:(1)Through the freeze-thaw cycle,uniaxial compression and triaxial compression tests on the prefabricated rock samples,the influence of the number of freeze-thaw cycles on the physical and mechanical properties of the rock is analyzed,the failure law and strength degradation law of the rock are revealed,the failure characteristics of the rock are analyzed,and three failure modes of tensile failure,shear failure and tensile shear mixed failure are proposed.(2)Based on the Lemaitre strain equivalence principle,the damage constitutive equation of rock under the coupling action of freeze-thaw and load is established,and the calculation formula of stress intensity factor of rock under the action of freeze-thaw and load is derived Rock stability evaluation method.(3)Based on the theory of unsteady temperature field with phase change and boundary theory of boundary layer,the boundary condition of slope temperature field with periodic temperature change is established,and the temperature field of rock slope in cold region considering time effect is simulated.Based on ABAQUS strength reduction method,the failure mechanism of rock slope in cold region under time effect is analyzed.With the increase of freeze-thaw specimens,the rock mass is more prone to failure and instability within the influence range of freeze-thaw.The first place to yield is at the toe of the slope,and the plastic zone changes along the boundary of freeze-thaw depth when extending upward,especially when the slope center is through,and the slope is behind The plastic zone of the part almost coincides with the depth line of freeze-thaw until the sliding surface of the slope passes through.By changing the location and depth of the fracture,the influence of the change of the location and depth of the fracture on the stability of the rock slope in the cold region is analyzed.It is concluded that with the increase of the freeze-thaw cycle time,the difference of the location of the fracture has little effect on the attenuation law of the slope stability coefficient,only reducing the number of the slope stability system;and the increase of the depth of the fracture will accelerate the attenuation of the stability coefficient of the rock slope.