目前针对塑料排水板处理地基的固结计算均采用传统的砂井固结理论,即需要将扁长的塑料排水板等效为圆柱体之后再进行分析,这种简化过程可能会带来一定误差。为此,将塑料排水板视为与其形状较为接近的椭圆柱体进行研究。首先给出椭圆柱坐标体系下的塑料排水板处理地基固结基本方程,并基于椭圆柱坐标系理论得到超静孔隙水压和固结度的解析解,讨论新的解答与已有经典解答之间的关系,认为经典的排水板周长等效法高估了排水板的排水固结效果。此外,讨论了排水板渗透系数kw随深度线性衰减和随时间指数衰减变化时的固结解析解,通过计算讨论认为,渗透系数随时间的变化对排水板地基固结影响最显著,参数A2值越大,排水板地基固结速率越慢,以致于排水板严重淤堵而丧失排水能力。
The consolidation process for foundations with prefabricated vertical drain(PVD) Of plate shape is normally analysed with the assumption of the vertical drain to be circular in cross section with equivalent area. Such simplification leads to the discrepancy between the assumed and actual shapes. In this paper, the cross section of PVD was assumed as an elliptic shape which is close to the plate shape. The basic equations of consolidation for the vertical drain under the elliptic cylindrical coordinate system were presented and the degree of consolidation was then obtained. Comparisons between the new and traditional solutions were conducted and discussed. The traditional methods were found to overestimate the drainage effects of PVD. The drainage coefficient of permeability decreases linearly with depth and exponentially with time. The larger well resistance leads to the slower consolidation and even to serious clogging of the drainage board.