Study On The Optimization Of The Structure And The Nonlinear Buckling Analysis Of Large-diameter Steel Jacking Pipe

The jacking pipe is a kind of trenchless technology, because it has little influence on the surrounding environment, in the case of large buried depth, better economy etc, has been widely used in engineering construction. With the wide application of high performance steel in the engineering, the jacking pipe also showed the trend of large diameter and thin wall. But with the ratio of diameter to thickness increasing, the jacking pipe is likely to buckling and damaging under the axial force, therefore the research of large-diameter steel jacking pipe has been attracting more and more attention.The paper reviews the research frontier of stability analysis and calculation theory of the jacking pipe. The nonlinear finite element analysis and implementation method of thin-wall shell in ABAQUS is studied, establishing the finite element model of large-diameter steel jacking pipe. Focus on the analysis of the influence of the soil around the pipe, the geometrical parameters of jacking pipe, external loading on the axial buckling behavior of steel jacking pipe, and the wall thickness of jacking pipe is optimized. The main work is as follow:(1)Established the nonlinear finite element model of thin shell and results were compared with the classical solutions and test results, verification of the model and the analysis method is correct and feasible.(2)The finite element model of jacking pipe and soil interaction were established. ABAQUS finite element software was used for the axial buckling analysis of large-diameter steel jacking pipe. Three aspects of the surrounding soil,the geometrical parameters of jacking pipe, external load were analyzed, a specific study of effect and regular of elastic modulus and Poisson ratio of soil, buried depth of jacking pipe, pipe diameter, pipe wall thickness, wall friction, surface load and other factors on the axial critical pressure of jacking pipe, provide a basis for future design.(3)Pipe under axial force, effect of diameter on the critical buckling pressure is greater, the smaller the diameter, the great the impact on stability, when the wall thickness is less than 0.5% of the diameter, the critical buckling pressure will decline; the diameter of the pipe wall thickness from 0.5% to 1%, the critical buckling pressure increases from 155 MPa to190MPa, more significant effect; pipe wall thickness is less than 0.024 m, larger than 4m in diameter, poor stability;because of the vertical compressive stress of the dam, buried depth is more than 3m,the greater the depth, the better stability of jacking pipe, buried depth is less than 3m,the stability and the buried depth of jacking pipe is nonlinear relationship; the dam height is low, the wall thickness is large, there is an optimal depth of jacking pipe,the stability is best; with the increase of wall thickness, stability is better buried in the depth of 3m and 8m; the increase of dam height offset part of the lateral soil pressure, improving the stability of jacking pipe; pipe-diameter is bigger, the more shallow the depth, influence of the dam height on the critical buckling pressure is greater; the small effect of elastic modulus, the increase of elastic modulus with the increasing of structure stability; the smaller influence of Poisson’s ratio of soil, the wall friction,the dam width of the critical buckling pressure.(4)For a large-diameter steel jacking pipe water engineering are studied by numerical, combining with formula and the stability calculation formula of jacking force the specifications given, the wall thickness of jacking pipe is optimized form axial stability and radial stability, put forward the corresponding suggestion.