| Hefei City is located in the center of Anhui Province and is a transportation hub.The overall terrain is relatively gentle.The terrain is generally high in the northwest and low in the southeast.The regional geomorphic unit is the Jianghuai wave plain.The Changfeng District(Meso-Cenozoic sedimentary area)in the Luxi stratigraphic division of the North China strata area in Hefei is a huge thick Meso-Cenozoic terrestrial clastic rock accumulation area.Most of the surface is covered by Quaternary brownish yellow,brownish yellow clay,and subclay,and there are modern alluvial layers distributed in the middle and lower reaches of the river.Located on the edge of the subtropical zone,it belongs to the humid climate zone of the northern subtropical zone with mild climate.The South Extension Line of Hefei Metro Line 3 starts at Fangxing Avenue Station,passing Yungu Road Station,Qingnian Road Station,Xianxia Road Station,Zhanqian Road Station,Ruici Road Station,Yunxiao Road Station and Xiapaihe Road Station,Finally,Guanyi Road Station.The landforms of the area where the proposed project is located are mainly first-level terraces and second-level terraces,of which Yungu Road and Qingnian Road are first-level terraces,and Xianxia Road,Zhanqian Road and Ruici Road are second-level terraces.The terrain is relatively flat,the groundwater types in the study area are mainly diving and weak confined water,the regional atmospheric precipitation is abundant,and it is the main source of groundwater recharge.The form of discharge is generally seasonal recharge of river water,and most of the deeper groundwater is slowly The underground runoff form is discharged to the outside of the area;another way to discharge is artificial exploitation.Collecting and sorting borehole data,hydrological and geological data in the study area,combined with the measured groundwater level data,this paper uses a variety of methods to calculate the anti-floating waterproof level of each subway station.By analyzing rainfall data and site groundwater level monitoring data for up to 2 years,using dynamic analysis to obtain precipitation difference plots,it can be concluded that from2011 to now it is a period of partial high water,and then using the annual dynamic curve analysis method,multi-year dynamics The curve comparison method and frequency analysis method respectively deduce the maximum groundwater level of each site as a reference basis for anti-floating waterproof level.A series of hydrogeological parameters were obtained through on-site pumping experiments,and then combined with stratum data,GMS groundwater numerical simulation software was used to establish a numerical model to predict the change of groundwater level,and the existing groundwater level observation data was used to identify and verify the established model.The overall groundwater level The fitting degree is good,and it can be concluded that the hydrological parameters and the boundary conditions of the model are reasonable,and can reflect the real situation of groundwater.The established model is used to predict the groundwater and then the reference value of the anti-floating waterproof level of the station can be obtained.After analysis and comparison,combined with a variety of methods to comprehensively determine the anti-floating waterproof position of each station are: The elevation of Qingnian Road Station is 11.68 m,the buried depth is 4.56m;the elevation of Xianxia Road Station is15.12 m,the buried depth is 2.86 m,in front of the station The road station has an elevation of 23.29 m and a burial depth of 3.29m;the Ruici Road station has an elevation of 16.60 m and a burial depth of 2.64 m.Through the pore water pressure monitoring data,it is found that the actual pore water pressure is less than the theoretical pore water pressure,and a certain reduction factor can be considered in consideration of a certain reduction based on the actual conditions of engineering geology in the region and previous experience.Figure [74] table [14] reference [63]... |
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