CONSTRUCTION MONITORING ANALYSIS OF AN DEEP EXCAVATION OF A SUBWAY STATION

It was analyzed the monitoring data of the deep excavation of a subway station in Zhengzhou，such as horizontal displacement of retaining wall，axial force of steel struts，surface settlements，etc． The results show that the excavation to the basement，the maximum horizontal displacement at 2 /3 depth of the pit wall is up to 7. 57 mm． And the monitoring value of the steel support axial force is far smaller than the design value，so the design can be optimized Changes in groundwater level shows that the station construction has not too much impact on the surrounding environment，the biggest bottom uplift value is 13. 8 mm，wall maximum horizontal displacement is 7. 5 mm， maximum surface subsidence is 2. 4 mm，which are far less than alert values，Monitoring data and the analysis show that，the support scheme of foundation pit with underground diaphragm with three-row support support is safe and feasible．