Abstract：
Considering that dewatering is essential for metro construction in water-rich sand strata, and using a typical section of the running tunnel from Hexi Station to Hedong Station as an example, the dewatering effect and its influence on the surrounding environment were researched in a test section in Qingdao based on an analysis of the physical and mechanical properties of the sand stratum, which had a high number of clay particles. The results show that groundwater can be lowered to a level between the invert and sidewall under normal conditions by tube well dewatering, but this will be difficult in a combined rock and soil stratum; lowering the water level of 3.57~4.73 m may cause ground settlement of-5.58~ -10.72 mm; the total ground settlements are -24.93~-75.72 mm, of which the settlement induced by dewatering is 14.15%~24.65%; the total building settlements are -18.37~-7.25 m, of which the settlement induced by dewatering is 17.40%~29.05% (about -5.1~-2.1 mm), showing that dewatering has little effect on the surrounding environment. Compared to construction with no dewatering, adopting tube well dewatering and condulet reinforcement can improve construction efficiency in dry seasons such as autumn and winter while it may induce a wide range of settlements in rainy seasons, which necessitates enhanced reinforcement strength of the stratum. The dewatering effect was also calculated by FLAC3D software, indicating that the calculated results agree well with the tested ones.
2016, Vol. 53 