The Research Of Design And Construction Of Suzhou Metro’s Foundation Pit Dewatering

Precipitation is very important in deep foundation construction, especially the rapid development in recent years subway underground engineering, excavation of precipitation is increasingly being valued by the designer and the builder. For deep excavation in order to make it safe and smooth and efficient completion of precipitation must be carried out to prevent the flow of sand pit, leaving the pit piping phenomenon caused by the collapse of other damage. Based on the Suzhou Metro Line 2 extension line Dushu Hunan station Dewatering Project, tubewells precipitation method for the study of the foundation pit dewatering design, and to determine the parameters of the pumping test by well dewatering, and parameters were checking to determine the feasibility of precipitation design. And through on-site study of the actual situation of the construction process dewatering well for precipitation design provides a scientific basis. The main contents of this paper are as follows:(1) According to the engineering geological, hydrological conditions, as well as to achieve the purpose of foundation pit dewatering, excavation analysis of risk exists, after security checking Inrushing stability analysis and design a reasonable dewatering well types, including tubewell structure, depth, quantity and plane position layout design.(2) In determining whether a reasonable construction scheme of precipitation, the need for pumping tests, groundwater seepage through the three-dimensional mathematical model to calculate, predict groundwater levels caused by spatial and temporal distribution of precipitation, so you can get more information about the water layer of hydraulic parameters; While confined aquifer water level can get an initial depth and hydrogeological parameters; single well and get the water out of wells required for the buck. By pumping test to test the rainfall situation in order to facilitate the detection of whether the requirements to achieve maximum precipitation.(3) Combination of monitoring and the surrounding environmental requirements, through the design of pit water level observation wells and bore water survey pit outside, so you can always observing the pressure drop in the case of pit water level at the time of precipitation construction, meanwhile, can be observed that due to pit dewatering and pressure caused by the precipitation situation outside pit water level change.(4) Construction of well dewatering technology and process research, the relevant specifications require strict control of its quality indicators, to ensure the construction quality dewatering well as the normal pit precipitation escort.(5) Through research, determine the actual pressure applied precipitation well plugging program.(6) At the same time, clear how precipitation may lead to the settlement of the surrounding formation to minimize the situation, given the appropriate measures precipitation designs.Through this study, the project of precipitation is better, Pit successfully completed, the flow of sand, piping and other risks pit does not appear, this precipitation design program provides some guidance for precipitation engineering similar projects for deep foundation engineering practice with a reference value and practical value.