Analytical Calculation of Instantaneous Liquefaction of a Seabed around Buried Pipelines Induced by Cnoidal Waves

Cnoidal wave theory perfectly describes nearshore wave characteristics. However, cnoidal wave theory is not widely applied in practical engineering because the formula for the wave profile involves a complex Jacobian elliptic function. In this paper, the approximate cnoidal wave theory is presented. Based on the Biot consolidation theory and the approximate cnoidal wave theory, an analytical solution for the pore water pressure around buried pipelines caused by waves is derived. In addition, based on the principle of effective stress, a theory of soil liquefaction around pipelines is proposed. The theoretical results were virtually identical to the results obtained in a practical flume test. Thus, the analytical method proposed in this paper is feasible. Further, the theory is applied to analyze the instantaneous liquefaction of the seabed around buried pipelines and the stability of the pipeline in the Chengdao oilfield.

Automated summary

The research focuses on the cnoidal wave theory to describe nearshore wave characteristics. A simplified version of the cnoidal wave theory is presented, along with an analytical solution for pore water pressure and a theory of soil liquefaction caused by waves around buried pipelines. The theoretical results were verified through practical flume tests, demonstrating the feasibility of the proposed analytical method. The theory was further applied to analyze instant liquefaction of the seabed and pipeline stability in the Chengdao oilfield.