Numerical Analysis And Analytical Solution Research On Buckling Of Large Diameter Steel Pipe Jacking During Construction

Pipe jacking method is a kind of underground construction method without slotting.Compared with slotting construction,it can greatly reduce the amount of earthwork,save the construction land and have less influence on the ground traffic.In recent years,pipe jacking construction technology has made great progress with the increasing of pipe jacking diameter,but the disturbance of construction to stratum is still unavoidable,which will still lead to the deformation of soil around pipe jacking.In addition,in the process of pipe jacking,the pipe jacking is easily buckled under the influence of soil around the pipe and vertical load,which threatens the construction safety.Therefore,it is of great significance to study the buckling of large-diameter steel pipe jacking for construction safety.Based on the construction project of large diameter steel pipe jacking by inverted siphon of Longchuan River in central Yunnan,the paper adopts the method of combining theoretical analysis,finite element numerical simulation and analytical analysis,based on the second development of UMAT,the numerical simulation of vertical deformation of soil induced by large diameter steel pipe jacking construction,the numerical analysis and analytical solution of buckling of large diameter steel pipe jacking construction are studied:(1)Using the UMAT provided by Abaqus,using the improved Euler algorithm with error control,the boundary surface model is developed again.Using the developed boundary surface model,the pipe jacking process of the inverted siphon project in Longchuan River is simulated by finite element method,and the vertical displacement induced by pipe jacking is analyzed.(2)Based on the inverted siphon project of Longchuan River in central Yunnan,a three-dimensional finite element model of large-diameter steel pipe jacking is established,and the buckling characteristics of steel pipe jacking under axial pressure are revealed through finite element calculation,the effects of soil and pipe-jacking parameters on critical buckling pressure and radial deformation of pipe-jacking are analyzed.The formula of allowable jacking force is modified by comparing the calculated value of the finite element method with that of the code,and the optimized formula of the stability coefficient of the pipe is deduced.(3)The calculation model of the axial buckling of steel pipe jacking in soil is established,and the analytical solution of the critical jacking force is derived by using the energy method,the correctness of the derived analytical solution is verified.Based on the analytical solution,the unstability jacking force of steel pipe in the inverted siphon project of Longchuan River in central Yunnan is calculated,and the influence of pipe length and diameter on critical buckling pressure is analyzed.