Impact Research Of Shallow Buried Rectangular Tunnel Under-crossing Existing Subway Bridge In Short Distance

With the rapid development of economy,the domestic urban land is more and more tight,the traffic congestion has become normal.In order to reduce the traffic pressure,the underground space is more and more developed,resulting in the complexity mixture of the above-ground and underground traffic buildings.The phenomenon that the tunnel across Bridges,tunnels,buildings,municipal pipelines and so on become more and more normal.The construction of new tunnel will generate negative impact on the existing building structure.Based on the existing subway viaduct project on the ramp of Longgang avenue in Shenzhen,this paper studied this process by means of numerical simulation and indoor model test.The main research process and results are as follows:(1)By means of numerical calculation,the deformation laws and characteristics of surface,tunnel and bridge substructure in the whole process of tunnel construction as well as the possible reasons were analyzed and summarized.(2)The process of demolishing temporary support lead to a marked impact on the earth's surface,ceiling,floor,the deformation of bridge structure.Therefore,this paper focused on the research of e process of demolition of the temporary support.Summarizing the rules and reasons of the deformations for piers,caps,bridge pier structure.(3)This thesis carried on the optimization research on the temporary support demolition scheme,using the method of numerical simulation to compare and choose the different demolition length schemes,and put forward a more reasonable temporary support demolition scheme,which can provide reference for similar projects.(4)Conducted the large-scale indoor model test,the process of dismantling temporary support was mainly studied.The trend and rules of surface settlement,the deformation rule of the bridge substructure fitted well with the results of numerical simulation,the demolition of the temporary support vertical scope and characteristics and the impact of lower part of the bridge structure were analyzed and summarized.