Experimental Study On Seismic Responses Of Anchored Slopes

Earthquakes often induce slope instability in mountainous regions,causing massive economic losses and casualties.Therefore,improving the seismic performance of slopes is a problem that needs to be solved urgently.In the support of slopes,prestressed anchor cables have the characteristics of good support,economy,and quick construction,and they have been favored and widely used by people in the industry.After the Wenchuan earthquake in 2008,it was found that the prestressed anchor cable slopes were damaged in different degrees,indicating that the prestressed anchor cables were not enough to withstand high-intensity earthquakes.In order to ensure the stability of slopes,ordinary anchor cables were optimized.New prestressed anchors:anti-seismic anchor.This paper studies the seismic response of anti-seismic slopes.Two models were made and small-scale shaking table tests were used to collect slope acceleration and cable strain dynamic response data to study the influence of ground motion parameters.The main conclusions are as follows:(1)The horizontal PGA amplification factor of the slope increases with the increase of elevation,mainly in the upper middle section of the slope.The anti-seismic cable has different seismic effects on different seismic waves.Under the elasticity condition,the amplification factor increases with the amplitude and enters the plastic state,and the amplification factor decreases.The seismic wave frequency and the natural frequency of the slope model The closer to the slope,the greater the PGA amplification coefficient;the duration of the seismic wave has little influence on the horizontal PGA amplification factor;the bidirectional coupling seismic wave weakens the seismic capability of the slope,and the acceleration peak amplification factor increases.(2)The vertical PGA amplification factor of the slope increases first and then decreases with increasing elevation,mainly in the middle and lower part of the slope;the type,duration,frequency,amplitude,excitation directions of the vertical PGA amplification factor The effect is similar to the effect of the level on the PGA amplification factor.(3)The amplitude of the seismic wave increases,the axial force of the anti-seismic cable increases nonlinearly,the axial force growth rate is greater than the amplitudegrowth rate,and the later growth rate increases;when the seismic wave frequency approaches the natural vibration frequency of the model,resonance easily occurs.The displacement deformation of the sliding body increases and the axial force of the anchor cable increases;when the holding body increases,the permanent displacement of the sliding body occurs,and the axial force of the anchor cable continues to increase;under the action of the bidirectional coupled seismic wave,the torsional vibration model of the model increases the instability and damage,and the anchor cable Increased axial force.The anchor cable has the largest axial force at the same sliding surface of the same anchorage.The anchor cable is bent at the sliding surface,and the free section is equivalent to the cantilever beam.(4)The seismic resistance of the upper row fails,the seismic wave amplitude is0.1g~0.5g,the slope slide force is mainly borne by the structural plane,the upper row of anchorage cables is in idle state,and the axial force of the lower row of anchorage cables increases linearly;when 0.6g,The shear plane appeared,the upper slide body moved slightly,the tension of the upper row anchor cable increased,the growth multiple was approximately 7 times,and the axial force of the lower row of anchor cables also increased sharply,forming a complete compression zone together.(5)The failure of the anti-seismic anchorage as a whole,and the axial force of the anchorage cable is divided into three stages: the appearance of the sliding surface,failure of the anti-seismic anchorage device,and sliding of the upper sliding body.The time-course curve is “stepped”.The amplitude of the seismic wave increases,the axial force of the anchor cable increases,and the duration of each phase shortens.After the vibration is completed,the sliding force is shared by the anchor cable and the structural surface,and the axial force of the anchor cable is consistent.This study provides some theoretical support for the design of seismic anchor cables for rock slopes under strong earthquakes.