Research of the Tunnel and Dewatering Technology under Complicated Environment Conditions

City center metro dense buildings need to make a long distance through the existing building (structure), resulting in ground tube well construction and more difficult operating conditions, precipitation, sedimentation control requirements have become more stringent. In this paper, starting from the rail transit construction, when restricted by the construction site, construction of tube wells proposed in the guide hole, and precipitation guide hole design, as well machinery and construction method are discussed. For additional settlement construction precipitation caused by the use of three-dimensional groundwater flow model coupled with land subsidence calculation software——Processing Modflow, establish coupling model of groundwater flow field and land subsidence, according to the on-site monitoring data, the model parameters using the modified, different designs pumping down the program, scheduled settlement prediction conduct timely analysis of the impact of construction on the surrounding environment of precipitation, and can guide a similar construction, the project has an important practical significance.