Research On The Settlement Control Technology Of Shield Tunneling Through Existing High-speed Railway Culvert Structures

The earth pressure balance shield has become the first choice for construction of Xi'an subway tunnel due to its wide adaptability to strata,high speed of excavation,and relatively low construction cost.However,it also has the disadvantages of difficulty in excavation control,large construction disturbance,etc.during construction in the sand layer.In complicated environments,engineering problems such as difficulty in control of shields,slow tunneling speed,and large surface subsidence often occur when excavating a full-face sand-clay soil pressure balance shield in a complex environment,which poses great difficulties in the protection of surface structures(structures)..In this paper,the Xi'an Metro Line 4 Shangxin Road ~ North passenger station shield tunnel underpass tunnel culvert under high-highpass railway as the engineering background,through indoor testing and numerical pre-analysis,provide the initial parameters for the shield construction.Combined with the real-time monitoring data and the numerical inversion analysis results of the test tunneling section,the shield tunneling equipment under the complex environment can provide reasonable excavation parameters and soil reinforcement schemes.In the process of formal promotion,construction parameters are adjusted dynamically based on construction monitoring data,and numerical analysis is used to optimize parameters during construction in complex environments.Intelligent monitoring is also used to ensure the safety of shield tunneling.The main research content includes:(1)Analyze the settlement data of the test section,and study several stages of the shield machine's influence on surface deformation caused by excavation in sandy soil layers,and use the method of theoretical analysis,numerical simulation,etc.to shield the sand machine in sandy soil.The settlement caused by excavation in the layer is reasonably predicted and the horizontal and vertical settlement patterns on the surface are analyzed.(2)Through indoor tests and other methods to find the optimal selection of the muck improver suitable for the shield machine to excavate in the full section of the sand in the construction section,and to analyze the surface settlement of the shield tunneling before and after the improvement of the muck.Impact,verify the rationality of the improved ratio of muck.(3)The numerical simulation analysis method was used to study the influence of the shield machine on the superstructure during the period of passing through the high-speed rail culvert risk source.According to the calculation results,the internal force of the verification structure meets the specification requirements,and the shield can smoothly pass through the risk source of the segment.(4)Study the main construction parameters(dig pressure,jack thrust,cutter head torque,excavation speed,unearthed amount,etc.)during the shield machine passing through the upper risk source.Summarize the value of reasonable tunneling parameters during the shield machine passing through the risk source.Scope and summarization of the reinforcement scheme during the shield machine's penetration of the source of the risk.(5)According to the intelligent monitoring data,analyze the impact of shield tunneling on the upper risk source,including surface settlement.Culvert settlement,culvert deformation,etc.,and compared with the data obtained from numerical analysis to verify the accuracy of the model analysis.