Study On Surrounding Rock Stability Of City Subway Tunnel

As is known to all，the conditions of underground engineering and groundengineering is completely different，and which is more complex relationship for largespan shallow tunnel. They have long used the "experience design","experienceconstruction" and the project analogism to design.With the development of UrbanRailway Transport, at the same time, there are many problems,and presently, urbansubway is directly related to the urban environment and its layout.The core,which is the design of the urban shallow tunnel engineering、constructionand the safe operation,is the analysis of the stability evaluation of the surrounding rock.This paper bases on key Project of Science and Technology of ChongQing, relying onbackground of ChongQing building rail transportation,which is subway line one、subway line three and subway line six. author bases on the knowledge of structuralmechanics, according to the similarity simulation experiment and numerical calculationresults, studying the load model of shallow tunnel and supporting structure stresscharacteristics.The main conclusions are summarized as follows:①With the help of the existing domestic data,author derived the basic formula,andensure surrounding rockmass pressure of subway station to get the load distribution lawon the shotcrete structure.②Through the formulas, author use it to apply some section of XiaoShenZi tunnelfor checking and calculation. conclusion is identical with the actual result,which isapplied in practice engineering to make the forecast on construction guidance.③Author gets excavation method, which is more suitable for large span shallowburied, through comparatively analyzing CD method and double benching tunnelingmethod. Basing on the pressure arch theory,writer establishs a standard of dividingshallow tunnel and depth tunnel.④Through soil mechanics experiments on the sample, carrying out the mixturetests of simulation materials and opening construction effect simulation test, authoranalyzes the law of of the strain on tunnel straight wall and surface settlement.⑤With the aid of the numerical simulation of construction effect on large spanshallow buried subway station, writer carrys out the three-dimensional finite elementnumerical analysis of elastic-plastic.comparing the similarity simulation experimentwith numerical calculation results,which is matched well, author puts forward the force characteristic of the structure, and guides similar tunnel construction.The result of this paper, which is guiding value for large span shallow buried tunnelconstruction, haves certain practical reference significance on similar project.