Physical modelling of pipe embedment and equalisation in clay: Fid-Bau Portal

Physical modelling of pipe embedment and equalisation in clay

V Meyer

Pipelines laid on the seabed are subjected to loads that may cause unacceptable displacements. On fine-grained soils, the capacity of a pipeline to resist these loads is affected by the pipe embedment and any excess pore pressures remaining in the surrounding soil from the laying process. This paper presents results from model tests, performed at near to full scale, investigating the embedment response and the subsequent pore pressure equalisation of a pipeline on a high plasticity marine clay. Existing models for the penetration and dissipation processes are compared with the experimental data. Conventional undrained bearing capacity theory, making minor allowances for strain rate and softening effects, shows good agreement with the observed penetration response. Dissipation solutions based on elastic and elasto-plastic soil models capture the general shape of the pore pressure response. The operative coefficient of consolidation varies between tests, spanning the range between the compression and recompression values observed in oedometer tests. The observations validate the theoretical solutions for penetration resistance, and highlight the uncertainty that must be considered in estimating equalisation times.