Study On The Failure Mechanism Of Anti-Dip Layered Rock Slope Under Seismic Force

In recent years,with the continuous large-scale construction of engineering projects in China,the number and magnitude of domestic slope instability accidents have increased annually,and the disasters caused by unstable rock slopes distributed in mountainous areas are staggering.Earthquakes play a critical role in inducing rock slope instability,which under seismic conditions exhibits characteristics such as a short cycle,wide extent,and potent destructiveness.The investigation of the failure mechanism of anti-dipping rock slopes under earthquake action provides a theoretical basis for the management and protection of landslides in earthquake-prone areas,and is of utmost importance in ensuring the safe construction and operation of slope engineering projects in mountainous regions.This passage is focused on studying the failure mechanisms of anti-dipping layered rock slopes in seismic regions.The investigation was conducted through theoretical analysis,numerical simulation,and other methods to analyze the mechanisms of rock mass strength degradation,and to reveal the instability mechanisms of anti-dipping layered rock slopes under earthquake action.The primary research content and conclusions are as follows:(1)Based on the principle of minimum energy consumption and combining the theories of damage mechanics and fracture mechanics,this article derives the damage constitutive equation and fracture failure criteria of rock under conventional triaxial compression conditions,and verifies the obtained formulas through comparative experimental results and numerical analysis,analyzing the damage evolution law and fracture failure process of rock.The study shows that under the influence of earthquakes,rocks induce the initiation and propagation of internal microcracks due to damage accumulation.When the energy consumption rate during the process exceeds the critical value,microcracks extend and form macroscopic cracks.The extension and penetration of macroscopic cracks ultimately lead to rock failure.The damage variable D of rocks remains zero in the elastic stage,and the damage threshold increases with the increase of confining pressure.The type I and type II fracture failure criteria derived based on energy principles are applicable,and the rock failure process conforms to the objective law of the principle of minimum energy consumption.(2)Based on the pseudo-static method,a simplified physical model of rock slope containing a set of dominant structural planes under seismic action is established.Two expressions of stress intensity factor at crack tip are derived based on fracture mechanics,and a method for dividing stable and failure zones of rock layers is proposed.The failure mode of the slope is determined by the rock block thrust derived from limit equilibrium theory,and the interlayer load is quantified to obtain a method for evaluating the overall stability of the slope under seismic action.Finally,the effectiveness of the method is verified by numerical analysis.The results show that under horizontal seismic action,the rock slope containing anti-dipping layers will first fail in the upper part of the slope,and then the failure will propagate layer by layer downward until the foot of the slope stabilizes.The failure mode is a chaotic distribution of toppling-sliding.With the increase of seismic impact coefficient,the failure in the upper part of the slope intensifies,and the failure mode gradually shifts from toppling to sliding,showing a decreasing trend in the overall stability of the slope.(3)Based on the ANSYS/LS-DYNA finite element analysis method and the conclusions of the previous chapters,the dynamic response process of the anti-dip layered rock slope was simulated and compared with the theoretical calculation results.The two were found to be basically consistent.The results showed that under earthquake load,the closer to the cliff face,the greater the shear deformation,and the stronger the dynamic load,resulting in the final failure surface of the slope being in a zigzag shape.By plotting the displacement curves of monitoring points with different joint dip angles,it was found that the slope deformation displacement became more pronounced as the joint dip angle decreased.The law of initial slope surface failure affected by earthquake wave intensity was obtained through calculation analysis.As the input seismic wave amplitude increases,the initial failure position of the slope surface shows a trend of moving from the middle of the slope to the top of the slope.