Remediation for buried pipeline systems under permanent ground deformation

Abstract

A remediation technique for buried pipeline system subject to permanent ground deformation is proposed. Specifically, expanded polystyrene (EPS) geofoam blocks are used as low-density backfill, thereby reducing soil restraint and pipeline strains. In order to evaluate this remediation technique, a series of 12 centrifuge model tests with HDPE pipe was performed. The amount or spatial extent of the low-density backfill was varied, as well as the orientation of the pipe with respect to the fault offset. Specifically, in the −63.5° test, the orientation was such that the pipe was placed in flexure and axial tension. The −85° orientation placed the pipe mainly in flexure. In all cases, the behavior of the remediated pipe was compared to that for the unremediated pipe. The geofoam backfill was successful in improving pipe behavior for two of the three pipe/fault orientations. However, for the 60° orientation, the pipe buckled in compression irrespective of the geofoam backfill. For compression, it is recommended that the pipe–fault angle be considered at the route selection stage to avoid compression loading.