Design Of A Pipeline Protection Structure Over Compressible Ground

This paper outlines the main geotechnical challenges associated with the protection of an existing major oil pipeline due to construction of an arterial highway within an area of compressible soils.

A detailed ground characterisation was carried out to understand the performance of foundation soils under embankment and traffic loading. This consists of a thorough interpretation of shear strength and consolidation characteristics to inform the design of a piled concrete slab protection structure. The design methodology was developed with the following three (3) key project drivers in mind:

• A solution that adopts piles to act as “settlement reducers” instead of a rigid piled alternative. The benefits of this approach are viewed through the lens of eliminating the formation of a so-called “hard point” within the road alignment measured at the pavement level.
• Mitigation of embankment fill stresses directly impacting on the performance of the pipeline.
• From a project perspective, the design aimed at achieving potential cost savings during the construction phase.

A 3D finite element model was developed in PLAXIS 3D to model the soil-structure interaction, coupled with a pipe stress analysis in ABAQUS 3D to model the soil-pile-pipe interaction and pipeline performance during primary and secondary consolidation.