Pipeline Embedment Prediction Using As-Laid Data

Pipe embedment defines the initial condition of the pipeline following installation and is fundamental to the calculation of both axial and lateral resistance of pipelines. However, the initial embedment depth of a pipeline is notoriously difficult to predict. The influence of cyclic loading during pipe-lay is known to significantly increase embedment. However, there is no known empirical work or data from which to model or predict the additional embedment associated with the dynamics of the pipelay operation. As-laid data from pipelines must be viewed as the best guide. Field survey embedment data are presented for a rigid pipeline installed in deep and shallow water clay sediments. These data are used to re-evaluate the models used for predicting the initial pipe embedment. Recommendations are given on the dynamic embedment factor required to account for the dynamic effects at the touchdown region during installation. The results demonstrate that the initial pipeline embedment is much more dependent on the dynamic installation loads and less on the stress concentration at touchdown.