Abstract: Longhu Financial Center Outer Loop Building Group Project is located in Zhengdong New District, Zhengzhou City. The entire development consists of 24 land blocks. The total area of the deep excavation is 285,200 m2, and the excavation depth is between 12.5 and 20 meters. The deep excavation project is very large, and the surrounding environmental conditions of the proposed excavated area are complicated. It is necessary to develop a safe, cost-effective and efficient groundwater control measures for the construction in thick sand aquifer layers. Before the implementation of the excavation procedures, a series of single dewatering well tests were conducted to obtain the hydrogeological parameters of the thick phreatic aquifer, to determine the reasonable design of the seepage cut-off wall. Since the groundwater cut-off curtain needs to penetrate the 20 meters thick fine sand layer with high SPT N values, the installations technique of Trench Cutting Re-mixing Deep Wall was used in areas with high environmental restriction requirements. Conventional three-axis cement-soil mixing piles were applied in the other areas.

Key words: deep excavations, dewatering point well group tests, uniform soil cement mixed wall by trd, groundwater control measures