ANALYTICAL SOLUTION FOR DYNAMIC RESPONSE OF BURIED PIPELINE UNDER CNOIDAL WAVE LOAD BASED ON PASTERNAK SEABED MODEL

A two-stage analysis method is used to explore the dynamic response of the embedded pipeline under the action of cnoidal waves. Based on the cnoidal wave theory, using the Biot’s consolidation equation, the periodic wave pressure on the buried pipeline in the shallow water area under the action of nonlinear waves is derived. The pipeline is considered as a Euler-Bernoulli beam on the dynamic Pasternak seabed model, and the obtained wave load is applied to the pipeline. Through the force analysis of the micro-element body, the results of infinite-length pipeline placed on the Pasternak seabed are obtained. The response controls partial differential equation of the pipeline under seepage force and dynamic load; the Fourier transform and Laplace transform are used to simplify the equation, and the analytical solution is obtained with the help of the convolution theorem. The pipeline dynamic response solutions of deflection, velocity, acceleration, rotation angle, bending moment and shear force are obtained. Through comparative analysis with three-dimensional finite element calculation examples and existing test data, the correctness and applicability of the theoretical solution are verified. The sensitive parameters of the dynamic response characteristics of embedded pipeline under the action of cnoidal wave are analyzed; The results show that the wave height H significantly affects the shape of the wave surface and the wave force in the seabed; Under different H, the changes of pipeline rotation angle, bending moment and shear force are more obvious, while the sensitivity of deflection, velocity and acceleration response is lower.