The Influence On Surrounding Environment Of Large Area Foundation Pit Dewatering

With the continuous development of china’s economic construction and engineering technology,a large amount of cities are carrying out the construction of “double city centre”,trying to build comprehensive development areas including multiple elements such as economy, entertainment, culture and so on. More and more large foundation pits have emerged,the scope of engineering construction continues to expand. In order to ensure a dry surface in the excavation of foundation pit and avoid risk factors such as quicksand and Pit-inrush,we need take the proper method of foundation pit dewatering according to the geological and hydrogeological conditions of project. As we know,excavation perviousness will change the groundwater environment,at present,many engineering researchers have been studying the influence of foundation pit dewatering on surrounding environment and have already made some achievements. However,when the excavation of foundation pit become deeper and wider,the construction of the project cycle extended,multiple foundation pits are in construction at the same time, the problem of foundation pit dewatering we will face is regional. The influence on surrounding environment of regional foundation pit dewatering have been paid more and more attention by people,such as the influence of water environment and the ground uneven settlement. According to the subject,we make a variety of simulation on different working conditions by using Modflow groundwater three-dimensional numerical simulation software to study the influence of regional dewatering on surrounding environment which is based on Tianjin Yujiapu financial construction district.According to the foundation pit dewatering design of Yujiapu first-stage project,making simulation of three different working conditions which are one area for foundation pit dewatering,two areas for foundation pit dewatering at the same time,three areas for foundation pit dewatering at the same time,and then make analysis of environmental influence due to simulation results. Next make the analysis of environmental influence of two large deep foundation,according to the simulation result,it can be seen when multiple foundation pit for dewatering at the same time,it will form a large area of regional dewatering and the sphere and impact of regional foundation pit dewatering will expand with the increase of drop depth and groundwater extraction causing the loss of water and the uneven settlement of the ground. In order to control the influence on surrounding environment,a certain amount of water control measures should be taken. Using numerical simulation software to make analysis of three control methods for foundation pit dewatering which are water-resisting curtain,arrangement of dewatering wells and effect of recharge well. In fact,the purpose of water control measures is to make minimum disturbance to the environment of foundation pit construction,on one hand,it ensure the safety of surrounding buildings and underground pipelines,on the other hand,it will save water resource,completing the requirements of economic construction and accomplishing environmental protection which is conductive to long-term development. From the results of numerical simulation,if we take measures to control water for foundation pit dewatering,the depth and breadth of surrounding environment influence is far less than take no measure. Further more,these three different water control measures have their own characteristics and advantages,possessing varying degrees effect to reduce the environmental influence. In real engineering,we can make a comprehensive analysis based on the characteristics of the region hydrological and geological conditions and engineering requirements,and then take effective and economic water control measures to ensure the foundation pit construction and make the minimum influence of surrounding environment,producing win-win situation of economic construction and environmental protection.