Analysis Of Surface Settlement Due To A Station Dewatering Of Changchun Subway Engineering

Foundation pit excavation of metro station and interval excavation under anhydrous or does not affect the construction of the environment and therefore prior to excavation must take precipitation and water stopping method, to ensure that the underground water level down to the excavation surface below 1m. Otherwise it will affect the normal construction of metro stations and sections. Subway precipitation project is different from the general foundation pit dewatering, with long construction period, reduce the water level, construction difficult feature. And subway lines are often built in the city’s bustling streets below, underground pipelines complex, surrounded with many buildings. Metro precipitation is inevitable to affect the surface subsidence and surrounding buildings, how much impact the need for quantitative analysis, and the impact of what the law, whether the surface and surrounding buildings damage, this is the purpose of this paper analyzes the impact of subway precipitation on ground surface subsidence.Because of the regional nature of geotechnical engineering, the groundwater depth of Changchun city is 1.90 ~ 3.30 m, and the depth of excavation is about 20 m, this paper analyzes the impact of the Changchun subway station foundation pit dewatering project on the ground surface settlement. This paper firstly introduces the background and significance of the research, analyzes the current situation and existing problems, and summarizes the characteristics and applicable conditions of the commonly used subway precipitation types; summarizing the influence factors of foundation pit precipitation scheme, and the design of dewatering and monitoring scheme for the foundation pit of a Changchun subway station; the general finite element software Midas/GTS NX to do a simple introduction, according to the geological survey report and the parameters of station support, the dewatering and excavation support of the local foundation pit of the station are simulated, the simulation results show that the precipitation funnel curve and the coupling effect of the group well are reflected, the numerical model of the influence law of the precipitation on the ground surface is found.By analyzing the result of precipitation on ground surface subsidence monitoring, the influence of precipitation on the ground surface settlement with time is obtained in Changchun Metro. According to the data analysis of ground subsidence monitoring data, the results of 95 days, the maximum change rate of surface subsidence 60-81 days, 88 days later, the trend of land subsidence is slow.Through the data analysis, the conclusion is drawn that the influence of precipitation on the ground surface settlement of metro station is in the controllable range.