复杂地层三维建模与深基坑地下渗流稳定性分析

3D Modeling of complex stratum and stability analysis of underground seepage in the deep foundation ditch

地下水渗流是引起基坑失稳工程险情的重要因素。为减小其对基坑开挖和周围环境的影响,以桂林市某基坑工程为例,利用FLAC 3D对基坑开挖及地下水渗流过程进行数值模拟,基于CAD体系构建基坑工程地质三维数值模型,显示出地下古塌陷的范围及其各土层之间的拓扑关系。采用流固耦合技术,对孔隙水压力进行计算,将模型模拟结果与现场实际观测结果进行对比调参,分析发现开挖基坑过程中,古塌陷附近开挖区孔隙水压力波动起伏大,同时古塌陷地下水有上涌的趋势,从而得出古塌陷区域孔隙水压力变化规律。为基坑开挖、施工提供建议,为深基坑地下水渗流稳定性问题研究提供参考。

Groundwater seepage is an important factor to threaten the safety of excavation.In order to reduce the threatening,a simulation of the ditch excavation and seepage process in Guilin City is carried out by FLAC 3D.The three-dimensional numerical model of foundation ditch engineering geology is constructed based on CAD system,which shows the scope of underground ancient collapse and the topological relationship between each soil layer.Then,the fluid-solid coupling technology is used to calculate the pore water pressure,as the parameters are adjusted to compare the model simulation results and field observation results.It is found that the pore water pressure fluctuates greatly in the excavation area near the ancient collapse,and the groundwater in the ancient collapse area tends to surge up,thus the variation regularity of pore water pressure in the ancient collapse area is obtained.It could provide some suggestions for excavation and construction of foundation ditch,and could also provide a reference for the study of groundwater seepage stability in deep foundation ditch.