Research On Construction Schemes Of Crossover Shield Tunnelling In Zhengzhou Metro Line 3

With the development of urban underground space in China,the construction of urban subway projects is also in full swing.The construction of urban subways is of great significance to alleviating the pressure of public transportation in large cities and promoting the economic development of the city.Based on the section of Erqi Square Station and Taikang Road Station of Zhengzhou Metro Line 3,this paper studies the construction scheme of the shield tunnel with overlapping sections in this section.The geological conditions of this section are complex and require high environmental protection.In this paper,numerical simulation is used to establish a three-dimensional numerical model by means of MIDAS/GTS NX finite element analysis software,focusing on the construction sequence of the overlapping overlapping sections in the interval,the longitudinal spacing of the face and the construction sequence of the small-span superimposed section,Grouting effect was studied.The main contents and research results of this paper are as follows:(1)Through the investigation and reading of relevant materials and literatures,to understand the latest developments in cross-overlay shield tunnels and small-pitch superimposed shield tunnels at home and abroad,focusing on the mutual influence effects of the first and second tunnels under different construction sequences.The impact on the surface subsidence and the analysis of the force of the shield segment,laying the foundation for the completion of the research of this subject;(2)Collect relevant cases of existing intersecting overlapping sections and small-pitch superimposed sections,and summarize the surface settlement,surrounding rock displacement and segmental force of similar working conditions(axial force,shearing force,bending moment,maximum principal stress,minimum main Stress,shear stress,etc.,provide verification materials for subsequent analysis;(3)Establish a tunnel model with a transition from left and right parallel to the upper and lower parallel,Through the simulation about different construction sequences("first up and down" conditions and "first down and then up" conditions),through the comparative analysis of the calculation results,the construction sequence that is more suitable for the tunnel in the cross transition section.;(4)Analyze the influence range of the tunneling after the cross-transition section on the existing tunnel,and obtain the reasonable longitudinal spacing between the first tunnel and the rear tunnel;(5)A superimposed section tunnel model with a clearance of 1.8m is established,and different construction sequences("first up,then down" working condition and"first down and then up" working condition)are simulated,and the comparative analysis of the calculated results is obtained.Construction sequence of small clear distance superimposed section tunnels in this interval;(6)The model of grouting reinforcement of small-pitch superimposed sections was established,and the calculation results of grouting reinforcement and not grouting reinforcement were compared to analyze the rationality of grouting reinforcement between two tunnels;(7)Suggestions on the construction plan of the Er?Tai section of Zhengzhou Metro Line 3?The research results of this paper will have certain guiding significance for the future research on the construction scheme of overlapping tunnels and small-pitch overlapping tunnels and it has certain guiding significance for the evaluation of the construction plan of the Er-Tai section of Zhengzhou Metro Line 3.