渗漏对武汉地区长江一级阶地地连墙结构基坑影响的离心模型试验研究

武汉地区长江一级阶地是典型的二元结构地层,承压水与长江和汉江贯通,地下水位的变化极易对该区域的基坑工程造成危害,尤其是当基坑地连墙存在渗漏点时。假设承压水位上升导致渗漏点出现渗水或流砂,渗漏点逐渐增大甚至会威胁地连墙稳定,或导致墙外地表下沉。以武汉地区某临江基坑为原型,采用离心模型试验,针对地下水位升高引起地连墙薄弱点出现渗透的问题,研究基坑的变形和稳定性。试验结果表明,当基坑地连墙上部预设薄弱点且承压水位超过地连墙薄弱点时出现渗漏破坏,造成的地连墙外侧地基沉降明显增大,且影响范围大,这与基坑开挖引起的变形规律显著不同。研究成果为武汉地区长江一级阶地受承压水位影响的基坑工程设计和施工提供参考。

Centrifugal Model Test on Influence of Leakage on Foundation Pit Diaphragm Wall in the First-level Terrace of Yangtze River in Wuhan

In the first-level terrace of the Yangtze River in Wuhan which is featured with typical dual-structure strata where the confined groundwater is connected with the Yangtze River and the Hanjiang River, the fluctuation of groundwater level would jeopardize foundation pit excavation, particularly when there is leakage point on the diaphragm wall. Assume that water or sand penetration is induced by groundwater level rising, the expansion of leakage point would threaten the stability of diaphragm wall or even give rise to ground settlement outside the wall. With a foundation pit excavation in Hankou, Wuhan, as a case study, we investigated the deformation and stability of foundation pit in the presence of leakage caused by groundwater level rising via centrifugal model test. In the presence of a weak point, when confined groundwater level rose above the leakage point, water and sand gradually penetrated, which further led to more significant settlement of the ground surface outside of the wall in a large scope. Such deformation differs from that induced by excavation. The research finding offers reference for the design and construction of foundation pits in the first-level terrace of the Yangtze River in Wuhan.