Calculation Of Seismic Displacement Of Pre-stressed Anchored Rock Slope Under Earthquake

China is a country with frequent earthquakes.Under the action of earthquakes,the rock slope is prone to slip and collapse,causing incalculable human casualties and damage to infrastructure.As a commonly used slope support structure,prestressed anchor cable is widely used in slope reinforcement.The investigation after Wenchuan earthquake shows that the slope anchorage technology has a good seismic reinforcement effect.However,at present,the research on the anchoring mechanism of slope and the stability evaluation under the action of earthquake is still not mature.Therefore,it has important theoretical significance and practical engineering value to study the reinforcement mechanism of anchor cable and the stability of anchored slope under the action of earthquake.In the dynamic stability analysis of rock slope,Newmark sliding block displacement method(also known as Newmark method)is a commonly used slope stability evaluation method.However,when calculating the seismic displacement of the anchored rock slope by Newmark method,the yield acceleration coefficient of the slope is generally assumed to be a constant value,and the effect of the real-time dynamic change of the axial force of the anchor cable caused by sliding block on the yield acceleration coefficient of the slope is not considered.For this,based on the theory of elastic mechanics are analyzed from the points of view of mechanics of the stiffness coefficient of anchor rod(rope)calculation method,and rock slope with prestressed anchor cable anchorage model as an example,considering real-time dynamic change of slope anchor axial force the yield acceleration factor,the influence of axial force is developed,with the consideration of anchor cable in the real-time earthquake dynamic effects of slope displacement calculation method,and the example analysis and model test verification.The main research contents and conclusions are as follows:(1)Aiming at anchorage rock slope,based on Mindlin displacement,this paper discusses the elastic limit of the anchor rod(rope)within the scope of pulling force and stiffness coefficient calculation method,analyzes the geotechnical layer parameters on the anchor rod(rope)when its tension free period of the influence of the total displacement and the displacement of anchorage segment,pointed out that in general the displacement occurs in the anchoring of rock and soil body should not be ignored,considering the displacement of the anchor rod(rope)stiffness coefficient more accurate.(2)Based on the quasi-static model,in view of the typical anchor rock slope,using the limit equilibrium method and Newmark method,considering real-time dynamic change of slope anchor axial force the yield acceleration factor,the influence of anchoring rock slope is deduced under the action of earthquake anchor axial force real-time dynamic change,the slope dynamic safety factor and real-time yield acceleration factor,the calculation expression,and the earthquake displacement of anchorage rock slope displacement after an earthquake is proposed to calculate the real-time dynamic sliding block Newmark displacement method.(3)MATLAB programming was used to calculate the seismic displacement process of the anchoring rock slope by calculating the axial force of the anchor cable,the dynamic safety coefficient of the slope and the yield acceleration coefficient of each earthquake interval with the recording time of seismic waves as the time interval,and real-time dynamic update was carried out.(4)Combined with the analysis of cases,the different slope parameters under the real-time dynamic sliding block Newmark displacement method and Newmark method to calculate the displacement difference after the quake,found that the real-time dynamic Newmark slidding displacement method is Newmark method to calculate the seismic displacement to smaller after the quake,and the differences between the two will decreases gradually with the improvement of the overall stability of slope,and with earthquake intensity and the anchoring section of the elastic modulus of rock mass and gradually increase.(5)Compared with the measured results of shaking table model test,the real-time dynamic Newmark sliding displacement method is closer to the measured results than the seismic displacement calculated by the Newmark method,which verifies the rationality of the proposed real-time dynamic Newmark sliding displacement method.