中文摘要：

波浪、潮汐作用引起临海、临江地区的地下水位周期性波动,基坑周围地基土的孔压响应机制是研究动水环境下基坑开挖课题的关键。假定有限厚度单层地基均质、各向同性,边界波动水位以正弦函数表示,将基坑渗流场分成3个区域,假设土体总应力不变,将固结方程解耦,利用Laplace,Fourier变换与逆变换推导得到浅层含水层内地下水位波动引起重力式挡墙基坑周围地基土孔压响应的二维半解析解。与PLAXIS有限元数值解的对比验证了该解答的精确性。通过算例分析坑外地下水位波动时基坑周围的孔压响应规律及其对重力式挡墙稳定性的影响。结果表明,沿坑外到坑内的基坑渗流路径,孔压的波动幅值不断衰减,滞后相位不断增大;挡墙稳定安全系数随地下水位的变化而波动,且存在相位滞后现象。

英文摘要：

Groundwater level in coastal region fluctuates periodically due to wave or tides. The response of the pore pressures of the ground near the retaining wall is vital for pit excavation. In this study,a single layer ground with finite thickness around the pit to be excavated was considered to be isotropic and homogeneous. The fluctuating water level at the boundary was assumed to be a sinusoidal function. The seepage area around the pit was divided into three zones. Assuming the total stresses of soil keeping constant,the two-dimensional consolidation equations were decoupled. A semi-analytical solution of pore pressure of the ground around the pit with gravity retaining wall in response to the groundwater level fluctuation was derived with Laplace and Fourier transforms. The comparisons with the results from finite element software PLAXIS verified the proposed method. An example was presented to investigate the pore pressure response around the pit and its influence on the stability of the retaining wall via the above semi-analytical solution. The results show that the amplitude of pore pressure attenuated along the seepage path from the back to the front of the retaining wall,while the phase lag increased. The stability of the retaining wall fluctuates and has phase lags too as the groundwater level fluctuating.