地震液化条件下地面的大变形三维数值分析

3D numerical simulation of large ground displacement caused by seismic liquefaction

地基液化条件下地面大变形是造成工程结构破坏的主要原因之一。考虑地形、地震、土层、地下水等影响因素,针对典型的岸坡场地3层土地基模型,利用有限差分法FLAC3D,对可液化场地在地震作用下发生地面大变形的过程进行了数值模拟。结果表明,临空面坡比愈大、地表坡度越陡,地基液化地表侧向位移值愈大;变坡度的场地在地震作用下发生的侧移要比单一倾斜率的场地大;地震最大加速度越大、地震持续时间越长,地基液化侧向位移、地表沉陷和隆起现象越严重;液化层的埋深、厚度以及地下水位都对地面大变形的产生有着不同程度的影响,应选择合理的地基处理方案进行处理。

The large ground displacement caused by seismic liquefaction is one of the main reasons which induce the failure of engineering structures.According to the typical three-layer foundation at sloping field,the process of the ground displacement due to liquefaction is analyzed by using FLAC 3D.The numerical simulation considers the main effecting factors,including the earthquake,topography,soil and groundwater characteristics.The results indicate that lateral displacements become larger when the gradients of the free face and ground surface increase.The lateral displacement of the site with variational gradients is larger than that of the site with single gradient.The surface lateral displacement,subsidence and upheaval become more serious when the ground maximal acceleration and earthquake time increase.The burying depth,thickness of the liquefaction layer and the ground water level affect the large ground displacement also.So,the reasonable ground improvement scheme should be considered according to the actual conditions.