Optimization Study On The Construction Scheme Of Embedded Metro Station With Overlapping Transfer And Large Arch Foot

With the accelerative implementation of new urbanization strategy,city population density increasingly increases,and public traffic space of urban ground gradually saturates in the current time,which requires us to develop underground space in the subjective and objective to improve the existing traffic situation,and increase the convenience of citizens’ daily travel,which is an effective solution to govern traffic jam in developed countries.Underground transportation is crisscross and convenient,and traffic flow is big in the transfer station,which puts forward higher requirements on its distribution function.Consequently,embedded metro station with large section and even super large section is increasing.At present,inland has built a few embedded metro stations with large section in arch cover construction method and accumulated a little experience,however,further studies for embedded metro station with super large span on this kind of construction method are needed,which is the context of this paper.This paper is based on Minandadao station of track loop,and employs synthetically survey literature retrieval,numerical simulation and field experiments to optimize the study on the construction scheme of embedded metro station with overlapping transfer and large arch foot.The research ideas are as follows:This paper summarizes the design and research status,as well as development tendency of super-span tunnel at home and abroad by means of literature retrieval,and the main studying contents of this paper are determined based on those.When optimizing the construction scheme of arch,this paper employs the large finite element software ANSYS establish four groups of two dimensional plane strain model for numerical simulation,and determines that both side headings of arch adopt three-step and around the turn of excavation method in virtue of research method of control variable.Then according to the differences between widths and excavation steps,this paper establishes six groups of two dimensional plane strain model for numerical simulation and select three-step construction scheme for core soil and its width is 5.6m and radius of initial support is 15.0m.When optimizing the excavation scheme of bottom,this paper determines three-step construction method in the light of the height of bottom.Then on the basis of the differences of slopes among different steps,this paper establishes two groups of two dimensional plane strain model for comparative analysis,and suggest that steps should choose the same slope of 700 at the process of bottom construction.When reinforcing large arch foot,this paper adopts mechanical construction in the range of 2.5m of large arch foot,and six-meter hollow grouting anchors and longitudinal beam are applied,at the same time,increase the thickness of sprayed concrete at this site.According to the results of finite element numerical simulation,the reinforce scheme is feasible.In the light of the construction scheme of arch,bottom and reinforcement of large arch foot,this paper establish a three-dimensional finite element model for elastic-plastic analysis on the basis of three-meter construction footage.Comparing with the site measurement data,the results prove that adopting this model can provide reference and guidance for actual construction.