| China is in the high-speed development period,while some problems need to be solved urgently such as population density and space tension accompanying large-scale urbanization.Therefore,the development of underground space,especially the construction of subway system,is particularly crucial.Nowadays,subway has become one of the main ways for residents to travel in most first-to third-tier cities,and has become an important lifeline of traffic in these cities.Once emergency arised,the traffic pressure would increase exponentially,even affect the normal operation of the city.Therefore,the safety of the subway system is extremely important.Besides,the safety of the surrounding construction is as important as the subway system as the lines are all over the city.It is urgent for the engineering construction to solve its influence on the safety of adjacent subway.Because of this,this paper starts from the foundation pit of a project under construction on the side of hefei metro line 1,which is adjacent to the subway tunnel and the station.MIDAS/GTS software is used to establish the model,and then finite element analysis is carried out on the basis of it,supplemented by some monitoring data for comparison,in order to study the tunnel structure of the side subway and the displacement variation law of the station and the exit part.In this paper,according to the different structures near the foundation pit,different supporting measures are adopted in different sections of the subway side,and the displacement changes of the tunnel,station and exit structure are obtained.In addition,the parameters of the retaining pile are changed in the supporting form,and the factors affecting the displacement change of subway tunnel,station and exit are analyzed to obtain the change law.The conclusions are as follows:(1)there are subway tunnels and station structures on both sides of the foundation pit,and the displacements of each part are obviously different.Different supporting forms adopted in sections can satisfy the construction quality and safety and give consideration to the project economy.(2)from the transverse view of the tunnel,the displacement of the inner tunnel structure is obviously greater than that of the outer tunnel.From the longitudinal view of the tunnel,starting from the tunnel far away from the station end,the tunnel deformation gradually increases along the longitudinal direction,and the change rangealso increases.At the midpoint,the variation amplitude begins to decrease,and the tunnel deformation increases until it reaches the peak at 3/4.Then the deformation began to fall back.(3)in the overall displacement,the transverse deformation of the tunnel decreases with the increase of pile diameter and increases with the increase of pile distance.The vertical deformation curve intersects near the midpoint.The settlement degree of the first half section decreases with the increase of pile diameter and increases with the increase of pile distance.The latter part decreases with the increase of pile diameter and increases with the increase of pile distance.The amplitude of variation presented regularity.With the increase of pile diameter,the maximum lateral displacement of tunnel and station decreases,while the maximum vertical displacement and the maximum two-way displacement at the exit both increase,and the change is linear.With the increase of pile spacing,the maximum lateral displacement and the maximum vertical displacement of tunnel,station and exit all decrease first and then increase,while the maximum vertical displacement of tunnel and station decreases all the time.Figure [94] table [12] reference [54]... |
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