可液化地基上边坡加固桩地震动力破坏特点研究

Study on characteristics of dynamic failure of stabilizing piles in slope on liquefiable soil foundation

采用研制的微混凝土抗滑模型桩,利用动力离心模型试验研究了高水位抗滑桩加固边坡的动力反应、动孔压变化、地基液化以及液化后大变形滑坡和动力断桩破坏规律。试验结果表明:由于动孔压上升较大,有效应力降低较多,导致动弯矩增幅较大,且动力附加弯矩值大于震前静力弯矩,表明地基液化与土体滑动导致的动力附加弯矩是抗滑桩产生断桩的主要原因。抗滑桩桩体完全断桩后,桩底静动总弯矩接近于零,嵌固约束完全失效,转化为活动铰约束。同时,饱和地基部分液化使得边坡上部土体的动力响应略有减小,加速度响应是随着高程先减小,然后略有增大。

By making use of model concrete piles,the dynamic centrifuge modeling test was performed to investigate the seismic response of slope and dynamic failure process of stabilizing piles in slope with high water level.The slide of slope surface and the crack failure of piles were observed during the earthquake.The results can characterize the distribution of response acceleration in the slope and the distribution of moment in the pile along with the accumulation of excess pore pressure.According to the observation and the test results,it can be concluded that the liquefaction of foundation makes the moment of pile increase sharply and results in the crack failure at the ends of piles.The liquefaction of foundation attenuates the acceleration response in the upper part of slope.