Buckling Of Imperfect Liner Pipe

Cured-In-Place Pipe liner used widely inpipeline trechless rehabilitation.The capacity to anti buckling caused by external pressure is the main design content of CIPP liner. The CIPP liner can be regarded as a thin wall cylindrical shell with external circumferential constraint, and the ultimate bearing capacity is mainly determined by the capacity of the lining to resistance to buckling. Researchers have explored the impact of different boundary conditions, material constitutive relationship and geometric imperfection on the capacity of liner to resistence buckling, but for the stability of the liner under the influence of the geometric imperfection, There is always a lack of rigorous and reliable mathematical models. The paper referring to classical Glock buckling formula, get the formula of critical buckling pressure under the influence of ovality, which is derived with the principle of minimum potential energy. The theoretical model are compared the verified finite element model.The results achieved in this paper show in following :(1) The critical buckling pressure of the deformed liner is obtained, and the R(s) is used as the control parameter, which is the radius of curvature.(2) The two-dimensional plane strain finite element model is established and the rationality and accuracy of the finite element model wad verified.(3) The load-displacement curves of liner with different geometery characters are obtained by using finite element model.The results in this paper not can be used in design of CIPP liner with ovality deformed. It is suitable for the calculation of the bearing capacity of the confined thin walled liner pipe which has the elliptical deformation. Such as HDPE liner or steel liner.