波动承压水下基坑底部弱透水层的非Darcy渗流分析

doi:10.16183/j.cnki.jsjtu.2019.036

摘要/Abstract

摘要：

为了更好地解释由承压水引起的基坑突涌现象，从渗流固结的角度出发，将Hansbo非 Darcy 渗流方程引入饱和土的Terzaghi一维固结方程中．采用有限差分法，求得由波动承压水引起的超孔压数值解，并将其退化到Darcy渗流情况与已有解析解进行对比，分析了非Darcy参数、承压水波动周期和初始水位对弱透水层超孔压变化规律的影响．结果表明：在波动承压水作用下，弱透水层中的超孔压随波动时间的延长而增加，若干周期后达到稳定波动状态．非Darcy渗流试验常数和直线段的起始水力坡降越大，超孔压的传递滞后现象越明显，振幅越小；承压水波动周期越长或者初始水位越高，超孔压的振幅越大；基坑底板承受的初始承压水位越高，超孔压受到承压水变化的影响越明显．工程应用的实例表明，考虑土体非Darcy因素时可以适当降低承压水位的设计下降深度．

关键词: 非Darcy渗流, 基坑, 超孔压变化, 弱透水层, 出逸比降

Abstract:

In order to better explain the phenomenon of foundation pit inrush caused by confined water, the Hansbo non-Darcy seepage theory was introduced into the Terzaghi one-dimensional saturated soil consolidation equation. Finite difference methods were applied to the numerical solution of excess pore pressure caused by the fluctuation of confined water. Then, the numerical solution was reduced to Darcy seepage and compared with the analytical solution. The effects of non-Darcy parameters, fluctuation periods of confined water, and initial water levels on the variation of excess pore pressure in the aquitard were analyzed. The results show that the excess pore pressure in aquitard volatility increases over time under the fluctuation of confined water, and reaches a stable fluctuating state after several cycles. The greater the initial hydraulic gradient and test constant of non-Darcy, the more obvious the hysteresis phenomenon of excess pore pressure, and the smaller the amplitude. The longer period of pressure water fluctuation or the higher the initial water level, the greater the amplitude of excess pore pressure oscillation. In addition, when the base is subjected to higher levels of initial confined water, the excess pore pressure in aquitard becomes more susceptible to the change of confined water pressure. The application of a case indicates that the designed drawdown depth of the confined water level could be reduced if the non-Darcy factor is considered.

Key words: non-Darcy flow, foundation pit, excess pore pressure response, aquitard, exit gradient

中图分类号:

TU432

应宏伟, 许鼎业, 王迪, 章丽莎. 波动承压水下基坑底部弱透水层的非Darcy渗流分析[J]. 上海交通大学学报, 2020, 54(12): 1300-1306.

YING Hongwei, XU Dingye, WANG Di, ZHANG Lisha. Analysis of Non-Darcy Flow in Aquitard at Bottom of Foundation Pit Under Fluctuation of Confined Water[J]. Journal of Shanghai Jiao Tong University, 2020, 54(12): 1300-1306.

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