地震作用下边坡预应力锚索振动台试验研究

为研究边坡预应力锚索在地震作用下的动力响应,采用振动台进行预应力锚索支护岩质边坡模型试验。模型试验相似关系依据重力相似律及量纲分析法推导。输入Wolong,El Centrol,TAFT三种地震波,监测锚索轴力、坡面加速度和位移时程,研究预应力锚索轴力和预应力损失在地震作用下的动力特性、边坡在锚索支护下的整体稳定性。结果表明:不同地震作用下,锚索的轴力和预应力损失动力响应不同,试验中锚索的预应力损失最大达15.7%,随着输入地震波峰值的增大,锚索预应力损失呈先增大后减小的趋势,达到临界值后,不再发生预应力损失。建议预应力锚索抗震设计时,施加的预应力应该达到预应力设计值的1.1～1.2倍,高于静力情况下的值。该研究结果可为更加合理的进行边坡预应力锚索抗震设计提供良好的基础。

SHAKING TABLE TEST STUDIES OF PRESTRESSED ANCHOR CABLE OF SLOPE UNDER EARTHQUAKE

the large-scale shaking table model test is adopted for study the behavior associated with earthquake shaking of the prestressed anchor cable retaining the slope.Similarity relation is derived by law of gravitivity similitude and dimension analysis method.Three kinds of seismic waves are inputted to study the dynamic response characters of prestressed anchor cable while the amplitudes of input seismic waves are increased.Axial force of prestressed anchor cable and the acceleration and displacement time history are monitored to study the loss of prestress and axial force of prestressed anchor cable subjected to earthquake shaking.Slope stability is also studied.The results show that loss of axial force and prestress of prestressed anchor cable varies with the change of input seismic wave.The maximum value of prestressing loss is 15.7% and with the increment of the peak value of input seismic waves,the prestresssing loss increased at first and then decreased to the critical value while prestressing loss is no longer occurred.It is proposed that the applied prestress value should be 1.1 to 1.2 times of the designed value of the prestress during seismic design of prestessed cable anchor,which is higher than the value under static conditions.