深基坑降水地下水渗流三维数值模拟

Three dimensional numerical simulation of groundwater seepage in deep foundation pit dewatering

长江中下游地区第四系松散沉积层深基坑降水一般采用非完整井,且由于深基坑周围连续挡水墙难以深入含水层底板,所以其地下水渗流场变化极其复杂,具有明显的三维非稳定渗流特征。以南京地铁中和村站—元通站区间隧道修复工程深基坑降水为例,基于深基坑降水三维渗流数值模拟的理论与方法,在概化出水文地质模型的基础上,建立了研究区深基坑降水三维渗流数学模型,模拟了在潜水含水层,微承压含水层复合存在、含水层最深底板埋深达56.01m、基坑周围连续挡水墙埋深为44至47m、抽水井井深达40m、抽水井过滤器埋深为26至38m,基坑内地下水位降至埋深达26.00m情况下的地下水复杂流动状态,并据此确定出了最优降水方案。

The partially penetrated well in the Quaternary loose sediment in the middle-lower yangtze area is always used for deep foundation pit dewatering. Due to the curtain wall is difficult to reach the aquifer bottom, the groundwater flow field is extremely complex with three-dimensional unsteady flow characteristics. In this paper,taking the dewatering of pit excavation works in the tunnel repairing between Zhonghe village and Yuantong station in Nanjing metro as an example,based on deep pit seepage theories and methods of three-dimensional numerical simulation and the generalized hydrogeology model,the deep foundation pit dewatering 3D mathematical model in the area to simulate the presence of multilayer aquifer is developed,the ground water flow state is simulated under the different conditions,such as the aquifer deepest bottom reaches 56. 01m,a continuous water-resisting curtain of 44 to 47m deep,pumping wells of 40m deep,the buried filters depth of pumping wells up to 26 to 38m,dewatering to the depth of 26. 00m under the pit base etc. The optimal dewatering proposal is determined accordingly.