Performance of Pipe-Soil Interaction Models in a Quasi-Dynamic Approach to Pipeline Stability Analysis

This paper presents performance of pipe-soil interaction models in a quasi-dynamic approach to submarine pipeline stability analysis. The quasi-dynamic method, as implemented in the PRCI-OBS software (Level 2), applies a series of most probable maximum waves to the pipe that are derived from extreme value analysis of the given sea state. The theoretical formulation for selecting the most probable maximum waves are derived for further clarity. The PRCI-OBS software (Level 2) was upgraded to allow for this study. The upgrade included addition of the well known Verley and Sotberg model for sand and Verley and Lund model for clay soils to the existing soil models known as PRCI soil models. The upgrade also included fixing previously reported bugs such as over-prediction of embedment in current-dominated cases. The matrix of performance simulations was sufficiently large to allow for making general conclusions. The results confirmed that the discrepancy between old and new soil models increased as the parameters approached extremities of the input matrix. The newly implemented models are based on larger model test data sets and could produce consistent results across the range of input data and thus are recommended.