Study On Key Technology And Engineering Application Of Double-Shield TBM Tunnel Construction In Hard Rock

Based on the Yangtaishan tunnel project of Shenzhen rail transit 6,this paper studies the construction stability of TBM tunnel under Guangzhou-Shenzhen-Hong Kong high-speed railway,and the construction stability of double shield TBM through fault fracture zone by combining theoretical prediction,numerical simulation and field measurement.The following research results are obtained:(1)Based on the random medium theory,a calculation method for settlement prediction of existing tunnels in the underpass construction project is proposed.The deformation of existing high-speed railway tunnels caused by different excavation sequence of TBM double-line tunnels is within the scope of construction control.The first excavation of Left-Line tunnels is conducive to maintaining the stability of surrounding rock and facilitating the actual construction.(2)The vertical deformation and the vertical dynamic stress of the soil at the bottom of the existing tunnel decreases rapidly with the increase of depth,When the existing tunnels are subjected to high-speed railway load.The main influence depth of high-speed rail train operation load on the soil at the bottom of existing tunnels is about 6m.The operation load of high-speed railway train has little influence on the newly built TBM double-line tunnel.(3)From the simulation results of double shield TBM crossing fault fractured zone,it can be concluded that different surrounding rock levels,different fault fractured zone width,different tunnel axis and fault fractured zone angle have different effects on Soil and segment.The deformation of segment and soil in fault fractured zone area is larger.(4)Based on the data statistics of the test section,the variation law of TBM tunneling parameters under different surrounding rock grades is analyzed,and the tunneling parameters of the key section of TBM are determined.Combined with the actual project,the auxiliary construction control measures are put forward,which effectively guides the construction of the key section of TBM with double shields.There are more and more construction projects of metro tunnels in China,and the number of new metro tunnels passing through existing buildings and unfavorable geological sections is also increasing.In this paper,the typical construction conditions of double shield TBM metro tunnel under existing high-speed railway tunnel and through fault fractured zone are analyzed in detail,and the construction impact and construction countermeasures are obtained.Some research results in this paper will provide guidance and reference for similar urban metro projects in the future.