Study On The Mechanism Of Water Level Rising And Application Of Diversion Measures In Subway Station During Operation Period

With the rapid development of economy and urbanization,the burden of urban transportation is increasing gradually.The construction of rail transit system has become the main means to alleviate traffic pressure in big cities.The construction of rail transit is a process of human intervention in groundwater seepage,which will cause significant changes in the original groundwater flow field and lead to high groundwater level,thus causing a variety of hydrogeological problems.How to carry out rail transit construction under the premise of protecting hydrogeological ecological environment has become a major scientific and engineering problem to be solved urgently.In this paper,based on the construction of the first phase of Jinan NO.4 Line project,the site of a subway station in Jinan is taken as the research area.The numerical simulation,theoretical calculation and construction of evaluation model are used to analyze the water level rise of subway station during operation and verify the application effect of diversion measures.The main research work and conclusions of this paper are as follows:(1)Based on groundwater seepage theory and geological environment characteristics of the study area,Three-dimensional modeling of the site area in the study area is carried out by numerical simulation software.The variation law of underground water level of subway station during operation period is studied.The distribution of water level of the facing and back water surface is analyzed.The results show that the maximum obstructing height of the facing water surface is 1.97m.The theoretical calculation is compared with the numerical simulation.The distribution law of water pressure in structure bottom plate is analyzed.The variation rule of leachate of groundwater level under different parameters is studied.(2)The application measures of subway station diversion engineering are generalized,and four diversion schemes are put forward.The numerical models are established to verify the diversion effect,and the variation rule of groundwater level is studied.The fluctuation state of groundwater level and the distribution of water pressure in structure floor after the application of four diversion measures are analyzed in detail.The diversion scheme is compared and selected,and the anti-floating fortification water level of 74.10m after the diversion measures are taken in the construction of the subway station construction.(3)Six indexes of high risk assessment of groundwater level are selected and the weight of the parameters is calculated.The TOPSIS decision theory method and the normal cloud model prediction method are used to build the high risk assessment system of groundwater level.The numerical simulation results are compared with the two evaluation methods.The results show that the normal cloud evaluation model has better application effect.Finally,reasonable suggestions are made for the high risk of obstructing water at different levels.