| With the development of the western region,the Belt and Road Initiative,sponge cities,urban subway planning and construction,Hubao Eyu urban agglomeration and other strategic plans,the Inner Mongolia Autonomous Region has entered a golden period of urban rail transit projects and comprehensive pipeline construction and development.Hohhot Rail Transit Lines 1 and 2 have been completed and operated,with a total length of about 50 kilometers and a total project investment of about 35 billion yuan.Limited by urban space resources,subway tunnels inevitably pass through the ground,underground buildings and structures.A new type of subway crossing-the new subway shield tunnel underneath the existing rectangular pipe jacking tunnel at a short distance has been successfully applied in the Hohhot subway.During the excavation process of the subway shield tunnel,the soil near the face of the tunnel will be disturbed,and the balance between the tunnel and the soil,the tunnel and the ground will be broken,which will cause the stress release of the tunnel base and the weakening of the supporting conditions,which may easily cause the existing The rectangular pipe-jacking tunnel produces excessive longitudinal uneven deformation,resulting in joint waterproof failure and even damage to the joint structure.In this paper,with the Hohhot Metro Line 2 shield tunnel passing through the rectangular pipe jacking underground passage of Hailiang Square as the background,on-site monitoring and measurement,BP neural network model and numerical simulation methods are used to analyze the longitudinal direction of the rectangular pipe jacking tunnel caused by the shield tunneling.The deformation and settlement laws,the settlement relationship between the shield machine parameters and the rectangular pipe jacking,and the evolution relationship between the opening amount and the offset amount are studied.Mainly get the following main research conclusions:(1)In the process of the shield tunnel passing through the rectangular pipe jacking underground passage of Hailiang Square,the parameters of the shield are analyzed,combined with the measured settlement data,and the value range of the construction parameters suitable for the Hohhot stratum conditions is obtained,which is Similar projects provide reference.(2)Through the analysis of the measurement points during the process of the newlybuilt shield tunnel with the left and right double lines under the two rectangular pipe jacking tunnels A and B,the three stages of the shield tunnel before,during and after the shield tunnel are compared and analyzed.The settlement and deformation law of rectangular pipe jacking tunnel is obtained.(3)Establish a BP neural network model,based on the settlement value of the existing rectangular tube tunnel obtained on site and the construction parameters of the shield machine,import the SPSS software for simulation to obtain the predicted value and the main parameters that affect the settlement value.(4)Use Midas GTS NX software to simulate the rectangular pipe jacking tunnel in the stratum structure model.According to the different spatial positions of the shield machine,that is,before,during,and after the crossing,analyze the opening and misalignment near the rectangular pipe jacking section.Changes in Taiwan volume. |
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