Application Research On Key Technologies Of Shield Tunneling Through Underground Traffic Corridor

With the vigorous development of urban underground space in China,the construction of new subway tunnels will be more and more close.However,the construction of the shield tunnel will disturb the surrounding soil,which will affect the nearby underground structure and even cause serious accidents such as cracking,damage or leakage of the underground structure.This article takes the underground transportation corridor of Xinghai Road under the section of Olympic Sports Center Station and Xingkong Road Station of Zhengzhou Metro Line No.14 as the engineering background.Based on the actual conditions of the project,the shield tunnel is worn under the topless soil and under the covered land.Referred to as the ring corridor,the two working conditions were separately analyzed and modeled.The variation law of the ring corridor displacement and additional internal force during the construction of the shield tunnel under the ring corridor is studied.The influence of different control measures on the settlement and additional internal forces of the ring corridor is analyzed.The reliability of the model is analyzed by combining the measured data and theoretical analysis.verification.The main research contents and conclusions are as follows:(1)The difficulty of this project is that the net distance between the new subway section and the ring corridor is small,and the minimum distance is only 0.5m.The under construction will have a greater impact on the corridor.According to the existing technical specifications,combined with the surrounding environment of the tunnel underpass and past experience,the control index of the corridor is determined:the vertical deformation control value is±10mm,and the maximum stress control value is±80 kN/m~2..(2)When the right line of the shield is worn under the topless earth ring corridor,the influence range of the ring corridor is about-12m~18m for the shield face excavation face,and the maximum value of the ring gallery settlement is 8.860mm.The maximum change of stress is 30.042 kN/m~2;when the left line of the shield is worn with the overlying soil ring corridor,the influence range of the ring corridor is about-15m~21m,and the ring corridor is set.The maximum value is 3.891mm,and the maximum value of the additional stress is 44.26kN/m~2,which meets the control standard.(3)Reinforcement of high-pressure jet grouting piles in the underlying soil layer can greatly reduce the settlement value of the uncovered soil ring corridor;as the back pressure at the bottom of the ring corridor increases,the settlement value of the ring corridor gradually increases,The stress is gradually reduced;when the right line of the shield is worn under the topless earth ring corridor,reducing the thickness of the ring corridor can reduce the maximum additional stress and settlement value of the ring corridor.However,when the shield is left under the upper cover,the upper ring is increased.The thickness of the large ring corridor can reduce the maximum additional stress and the settlement value of the ring corridor.(4)The measured data of the project shows that during the construction of the shield under the right line,the maximum settlement of the ring corridor is 6.2mm,which meets the standard value of settlement control value±10mm;the maximum additional stress change value of the ring corridor is 99.22 kN/m~2,already Exceeding the control standard value±80kN/m2,after the post-grouting,the additional stress of the ring gallery decreased from 123.05kN/m~2 to 77.18 kN/m~2;during the construction of the left line of the shield,the maximum settlement of the ring gallery was 2.6mm,the maximum additional stress change value of the ring corridor is 44.26 kN/m~2,which meets the control standard.