Study On Jacking Construction Technique Of Double Channel Rectangular Pipes Crossing Urban Road

With the continuous development of urban construction,urban traffic flow expands rapidly,resulting in increasingly significant urban traffic congestion.It is one of the important ways for the construction side to solve this problem to adopt the underground passage and other measures to realize the three-dimensional intersection.Based on the Jiangdongmen underground pedestrian crossing project in Nanjing,a mechanical analysis model of the construction process of double-passage pipe jacking is established,and the finite element analysis and experimental study of the pipe jacking and surrounding soil during the construction process are carried out.The main research contents are as follows:Rectangular jacking pipe has obvious advantages in section utilization and adaptability of shallow overburden soil.In view of the common problems in construction,the influence of the construction of the second passage on the first passage is studied through the numerical simulation and model experiment of the finite element method in the construction process of the double-passage pipe jacking,and the construction measures to ensure the forming quality of the double-passage are put forward.The construction of the left line will squeeze the soil on the right line,so as to improve the strength of the soil on the right line.The construction of the right channel will disturb the left line again,and the final maximum of the settlement curve will deviate from the left line.During the construction of the right line,the effect on the left line in the early stage is in the buried depth section of overburden soil,that is,the depth is lower than 6m,and the effect on the upper 6m is less.The construction measures of the back top passage are put forward,that is,after the first top passage is completed,the well joint is made in time,and the prestressed tension and grouting are implemented.During the construction of the rear roof passage,the 50 cm soil mass in the middle is monitored.Based on the analysis of the monitoring data obtained from the field test,the law of soil deformation caused by double-passage rectangular pipe jacking with small spacing is obtained.At the same time,in view of the possible environmental damage caused by the construction of double-channel rectangular pipe jacking,the construction solution and control scheme are proposed,including matching the jacking speed and the excavated speed,synchronous injection of thixotic mud,implementation of deviation correction,installation of door sealing ring,check device,mud replacement and so on.In this paper,the mechanical analysis and experimental results of the construction process of double-passage pipe jacking can provide useful reference for similar projects.