渗透各向异性土层中基坑二维稳定渗流半解析解

通过将基坑周围渗流场分为2个规则的区域,利用Fourier变换推导渗透各向异性土层中基坑二维稳定渗流的半解析解.根据与有限元软件PLAXIS计算结果的比较,验证了半解析解的正确性.基于半解析解,分析渗透各向异性、基坑宽度、挡墙距不透水层顶面距离、基坑内侧水位对挡墙两侧总水头分布的影响以及出逸比降随上述参数的变化情况.分析结果表明：二维渗流下挡墙两侧总水头为曲线分布；随着水平与竖向渗透系数比α、内侧水深d2的增大和基坑半宽度b的减小,挡墙两侧的总水头逐渐增大.随着挡墙距不透水层顶面距离L的增大,挡墙外侧的总水头逐渐减小,挡墙内侧的总水头逐渐增大.随着α、L的增大,b、d2的减小,出逸比降不断增大,基于一维渗流的出逸比降的计算结果偏不安全.

Semi-analytical solution for two-dimensional steady seepage around foundation pit in soil layer with anisotropic permeability

The flow region around the foundation pit in a soil layer with anisotropic permeability was divided into two regular parts. Then a semi-analytical solution for the two-dimensional steady seepage was obtained using Fourier transformation technique. The solution was verified through the comparison with the results obtained from the finite element software PLAXIS. Based on the semi-analytical solution, the effects of the ratio of horizontal permeability to vertical permeability α, the distance between the retaining wall and the impervious boundary L, the water level inside of the foundation pit d2, the half width of the foundation pit b on the distribution of water head along the retaining wall were analyzed, and the variations of exit gradient with the parameters were studied. Results show that the distribution of total water head along the retaining wall is curvilinear under two-dimensional seepage. The total water head becomes larger, as α, d2 becomes larger and b becomes smaller. As L becomes larger, the total water head outside and inside of the retaining wall becomes smaller and larger, respectively. The exit gradient becomes larger with the increase of α, L and the decrease of b, d2. It is unsafe to calculate the exit gradient under the assumption of one-dimensional seepage.