Interaction Relationship Of Pipe-slurry-soil And Resistance Reduction Technology During Deep Pipe Jacking With Long Distance

With the rapid urbanization and urbanization process in China,urban land resources are increasingly tense,and the deep underground space has become the land resources in the development of metropolis.Pipe jacking is a kind of trenchless technology to develop and utilize urban underground space resources.Because of its small construction disturbance and green environmental protection,more and more attention has been paid to it.However,in the process of deep pipe jacking with long distance,there are many problems,such as too much friction resistance,insufficient jacking force,stratum disturbance,and easily out of control jacking direction.In this paper,based on the deep pipe jacking tunnel project with long distance of the sewage transmission system in the core area of Dadong Lake in Wuhan City,the interaction of pipe-soil-slurry in the process of deep pipe jacking with long distance is analyzed by using the methods of field investigation,theoretical analysis and numerical simulation.Three kinds of pipe-soil-slurry contact mechanical models are established,which are suitable for different models The jacking force formula reveals the law of soil disturbance evolution around the deep pipe jacking process with long distance,and proposed the friction reduction technology during the deep pipe jacking process with long distance.The main research results are as follows:(1)The interaction among pipe-soil-slurry during the jacking process is studied,the influence of slurry on the jacking force is analyzed,and the jacking force formula suitable for different pipe soil slurry actions is determined.The larger the contact area between the pipe and the slurry,the smaller the jacking lift,indicating that controlling the distribution of mud plays an important role in reducing jacking friction.The jacking force of the pipe-soil full contact model is not much different from that of the pipe-soil full contact model when the arching effect is considered,but it is far different from that of the tube-soil full contact model when the arching effect is not considered.The longer the jacking distance is,the larger the jacking force required will be in a positive proportion.For jacking force with different burial depths,the jacking force will not increase significantly as long as the mud state can be kept in full contact with pipe slurry.Therefore,it is necessary to ensure sufficient mud and maintain full contact with pipe slurry in pipe jacking projects of deep burial and long distance.(2)This paper analyzes the influence of pipe jacking process with different depth on the surface,and reveals the characteristics of the distribution of surface settlement caused by pipe jacking process with different depth.The deeper the pipeline is buried,the less the impact of pipe jacking on the surface is.Moreover,the surface settlement value on the cross section along the direction of pipe jacking is symmetrically distributed along the axis of pipe jacking.The maximum vertical displacement is generated at the axis,and the closer it is to the axis,the greater the displacement value is.It can be concluded that the impact of deep pipe jacking on the ground is very small,so in the engineering geological conditions of this paper,the ground settlement can be less analyzed.(3)This paper studies the vertical displacement of different sections of surrounding soil in the process of long-distance pipe jacking,and reveals the law of soil disturbance evolution in the process of long-distance pipe jacking.In the process of pipe jacking,the soil above the axis will subside and the soil below the axis will swell.The simulation results show that the soil above the axis will be disturbed more than the soil below the axis.For pipe jacking with an outer diameter of less than 2m,the soil within a radius of 4m with the central axis of the pipe jacking as the origin can only be disturbed Carry out analysis and research.(4)This paper analyzes the relevant construction technology of pipe jacking in the actual project,and puts forward the friction reduction measures in the process of deep buried long-distance propulsion.In engineering practice,in consideration of the long distance of pipe jacking,the ability to flexibly adjust pressure and flow should be maintained at any position along the pipe jacking,so as to make irregular grouting;For the selection of relay should follow the experience,but also to consider the actual situation,specific problems specific analysis;The control of the axis should be rectified along with the deviation,and the deviation should not be too large.They were 48 picture,3 tables,and 121 references.