Influence Of Excavation Dewatering And Reinjection Of Subway Station On The Surrounding Environment

With the development of urban rail transit,subway has become the main mode of transportation in large and medium cities.In the process of subway construction,various problems in foundation pit projects will inevitably be encountered.Comparing with general excavation engineering,subway station excavations have the characteristics of large environment depth,complex surrounding environment,and many underground pipelines.Among them,groundwater is an important issue affecting the stability of excavation environment.Different precipitation recharge methods and design schemes are used in different regions and their geological conditions.Currently,there is no corresponding national code for precipitation recharge.Thus,there is a certain blind design of the excavation precipitation scheme.At the same time,the soil-related parameters have certain unknown effects on the surrounding environment under the conditions of the excavation precipitation recharge.In summary,relying on the Jinan Rail Transit Line R1 excavation project and combining with the unique engineering geological and hydrogeological conditions in the area,this paper based on ABAQUS random parameter analysis studies the influence of different precipitation recharge parameters on the hydrogeological environment around the excavation,which aims to guide similar excavation precipitation recharge projects.the following contents are mainly studied:(1)According to the data obtained from recharge test on the site,the influence of recharge pressure on surrounding water level,settlement and pore water pressure of soil at different depths are studied.The results show that the rising height of water level is directly proportional to the increment of recharge pressure,and the recharge pressure also affects the upward deformation of surrounding soil and pore water pressure.(2)For the anisotropy and variation coefficient of soil permeability coefficients,the influence of different horizontal permeability coefficients and vertical permeability coefficient ratios on the variation of soil permeability coefficients on the precipitation curve is studied;by ensuring the coefficient variability of vertical permeability is 0.Only the variability of the horizontal permeability coefficient is considered.The influence of the variability of the horizontal permeability coefficient on the precipitation curve is studied.It is concluded that the relative size of the horizontal permeability coefficient and the vertical permeability coefficient will affect the precipitation curve,and the variability of the horizontal permeability coefficient will change the head height near the precipitation well.(3)For different precipitation recharge depths and spacing of precipitation recharge wells,the influence of the parameters of the precipitation recharge model on the surrounding Environment is studied.The results show that there is a linear relationship between the difference in precipitation depth and the difference in surface subsidence,and a linear relationship between the difference in recharge depth and the difference in surface uplift.The distance between the recharge well and the settlement well has a certain effect on the surface deformation.(4)For the variability of the soil parameters of c,?,and E,the variability of a certain parameter is considered separately and the variability of the three parameters is considered together.The influence of soil parameter variability on the surrounding environment of precipitation recharge in excavation was studied.The results show that it is unreasonable to consider only the variability of a certain parameter;the variability is not the same as the ground deformation law derived from the mean simulation;the magnitude of the parameter variability has a certain fluctuation on the surface subsidence curve.