截排减压抗浮系统在抗浮事故处理中的应用

Application of interception and drainage anti-floating system in treatment of uplift accidents

对出现上浮事故的地下结构进行处理过程十分复杂,因为重新施工桩或锚杆需要大面积破坏底板,而盲目排水减压则可能对周边环境产生影响。截排减压抗浮系统是对该类事故进行处理的良好方式。其理念在于,利用基坑周边止水帷幕形成相对封闭的地下水环境,拦截外部大部分流量,同时利用底板上的减压井排水,并辅以观测及自动控制措施,实现自流自排。排水构筑物采用大直径减压井,降低了井周水力坡降,消除了产生淤堵的水力条件,同时方便后期的清理维护。减压井为预制无砂混凝土井环吊装而成,施工过程简单方便。该系统成功应用于地下车库的上浮事故处理,监测结果表明：流量及水头可控,且运行成本低廉。

It is very complicated to deal with the uplift accidents of underground structures, because the reconstruction of uplift piles or anchors will damage the wide range of bottom slabs, while draining water blindly to relieve pressure may have a bad impact on the environment. The interception and drainage anti-floating system is a good solution to deal with these uplift accidents. The concept of this system is to intercept and drain water by use of the cutoff wall around the underground structures to form a relatively closed seepage environment and several relief wells on the bottom slab. This system can discharge water automatically with the help of controlling and monitoring equipments. The hydraulic gradient around the relief well decreases dramatically due to the adoption of a large well diameter that offers convenience to the later cleaning and maintenance work, which eliminates the hydraulic condition of well clogging. The relief well consists of several prefabricated non-fines concrete well rings installed by crane, so the construction process is very simple. This system has been successfully applied to the treatment of the uplift accident of an underground garage. The monitoring results show that the flow rate and hydraulic head can be controlled, and the operating cost is low.