| Now,our country’s economy shows a rapid development in the course of the times,accelerating the process of urbanization,thus promoting the construction and development of urban subway tunnels.Currently shield machines are used by most cities for the construction of subway tunnels.And in cities,using the shield method to build subway tunnels,it is often necessary to traverse through pre-existing infrastructure.Therefore,in shield construction,the safety and rapidity of construction should be guaranteed,as well as that of ground built(build)buildings.This paper is based on the practical background of Lianlian Town Railway Engineering under a shield from Huai ’an East Railway Station,in order to guarantee that the sedimentation value of the Lianlian Town railway foundation is within a safe range during the process of shield wearing Lianlian Town Railway,and to guarantee the safety of Lianlian Town Railway.In this paper,the following conclusions are drawn from the analysis of theoretical calculations,model tests,numerical simulations,and on-site monitoring for the rational setting of pressure in a high railway foundation pond beneath a shield,as well as the deformation law of the foundation:(1)Through a brief introduction to an overview of Railway Engineering in the punctured town under shield from the Huai’an east station,we conclude that the main soil traversed by this engineered shield is water rich sand;we analyze the impacts on barn pressure from three aspects: the pressure on tunneling,the characteristics of the shield machine itself,and the surrounding environment,and propose corresponding technical control measures.We use the calculation method of soil and water monitoring to shield the normal tunneling segment.Using the equal load method as well as the earth mechanics knowledge to calculate the additional stress on the Lian Town Railway Foundation,we can obtain the calculation method of soil pressure on the railway soil bin under shield,and replace the values of each parameter by the theoretical value,which is 92.39 ～ 198.93 k Pa,to provide the basis for subsequent numerical simulation calculation;(2)Theoretically analyze the surface settling stage of shield excavation for a total of five stages,with barn pressure mainly affecting the surface settling stage II,while carrying out shield excavation chamber model tests to verify the surface settling stage of shield excavation from sedimentation diachronic changes,and analyze the sink change law;(3)According to the Huai ’an East Railway Station shield engineering as a practical engineering background,using Midas GTS finite element analysis software,we analyze the effects of the deformation law of the Lianlian Town Railway base and the change in the height of the base on the setting range of the pressure in the earth bin under different conditions of pressure.Mainly from the analysis of the changing trend and magnitude of sedimentation values of the lateral and longitudinal displacements of the Lian Town Railway substratum,we identify the scope for a reasonable setting of the soil bin pressure across the Lian Town Railway under shield,and how the soil bin pressure is set under the varying conditions of the base height;(4)Based on the on-site monitoring data,actual barn pressure values were collated using Origin,and a commonly determined barn pressure range from theoretical calculations to numerical simulation calculations was compared with that of a shield’s actual barn pressure range,both of which were comparatively analyzed to verify the applicability of this method for determining the barn pressure range,and transverse and longitudinal sedimentation values of the Lianlian Town Railway were collated and analyzed took the rule of the deformation of the basis at the singlet tunnel and that at the double tunnel.Figure [52] Table [7] Reference [71]... |
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