深基坑降水三维变参数非稳定渗流与地面沉降耦合模型

为了精确模拟预测松散沉积层中深基坑降水引起的地下水渗流场和地面沉降的变化特征，考虑土体孔隙度、渗透系数、储水率随地下水位下降发生的动态变化，建立了深基坑降水三维变参数非稳定渗流与太沙基一维固结理论的地面沉降耦合模型，并采用有限元数值分析方法对模型进行求解。以南京地铁三号线浦珠路站深基坑降水为例进行模拟计算。结果表明：采用15口坑内抽水井，抽水井过滤器埋深为22.0～37.0 m，基坑围护连续墙底部埋深至41.5 m为最优降水方案；不仅使基坑内地下水位满足开挖要求，又使基坑外地面沉降在控制范围内。经验证，所建立的模型合理，计算结果可靠，研究理论用于模拟预测此类地区深基坑降水引起的地下水流场变化具有较高的可信度。

Coupling Model of Groundwater Three Dimensional Variable-Parametric Non-Steady Seepage and Land-Subsidence

In order to accurately predict the dynamic characters of groundwater seepage field and land subsidence caused by dewatering of deep foundation pit in loose sediments, a ground settlement coupling model was established in this study. In this coupling model, three dimensional variable-parametric non-steady seepage of precipitation of deep foundation pit and one-dimensional consolidation theory based on Terzaghi were used. The porosity, permeability coefficient and water storage dynamic changes with the decline of groundwater level were also considered. And a three dimensional fem numerical method was applied to solve the model. The dewatering of the deep foundation pit in Puzhu Rd station, metro line 3, in Nanjing was taken as a case study. The results showed that an optimal project was obtained by adopting 15 dewatering wells for the pit, locating the filters of the pumping wells at depth of 22.0-37.0 m and defining a pit’s diaphragm wall at a depth of 41.5 m. By using this project, groundwater level could meet the excavation requirements and surface settlement outside the pit could also be within the controlled limits. The coupling model proposed was proven reasonable and reliable. And it has more credibility to use the theories in the article to simulate and predict the groundwater flow in deep foundation pit dewatering in similar areas.