地下连续墙支护全封闭式基坑降水试验研究

Experimental Research on the Dewatering of Closed Excavation with Retaining Structure-Underground Diaphragm Wall

以某大型地下连续墙全封闭式深基坑工程为例,通过抽水试验采用泰斯配线法获得的深厚承压含水层水力参数设计降水试验,通过试降水试验检验地下连续墙的止水效果以及降水方案的可行性。试降水试验结果表明,在12 h的抽降水过程中坑外混合井和承压水水位变化较小,地下连续墙的隔水效果良好;坑内均匀分布观测井水位均能够满足基坑土方开挖对地下水位的要求。因此,对于大型地下连续墙全封闭式深基坑工程开挖降水前的试降水是必要的,一方面可以验证地下连续墙的隔水效果,另一方面可为进一步优化降水方案提供基础数据。

Based on a closed deep excavation with retaining structure-underground diaphragm wall engineering, and through pumping test and by the method of thesis, the hydraulic parameters of deep confined aquifer were acquired and the dewatering test was designed. The water sealing effect and the feasible of dewatering program were testified through the pre-dewatering test. The results of the pre-dewatering test indicated that the water lever of mixed wells outside the excavation and confined wells changes rather small and the water sealing effect works well during the 12 h dewatering process; the observation wells which are evenly distributed in excavation can satisfy the demand of underground water lever in the process of soil excavation. Therefore, it is indispensable, for large deep excavation with retaining structure-underground diaphragm wall engineering, to conduct pre-dewatering before dewatering process in excavation. On the one hand, the pre-dewatering test can testify the water sealing effect of underground diaphragm, on the other hand,it can provide data for the optimal designing of dewatering program.