Use of tire-derived aggregate for seismic mitigation of buried pipelines under strike-slip faults

Compressible materials can be backfilled in the trench to reduce the soil restraints on buried pipelines at fault crossings. The potential of using tire-derived aggregate (TDA) as a backfill material for seismic mitigation of pipelines is investigated herein. A continuum-based three-dimensional finite element model for pipelines with trench mitigation is calibrated against experimental measurements. A comparative study is then performed to assess the impact of trench configurations and soil/pipe properties on TDA mitigation. Results indicate that TDA mitigation can generally increase the critical fault offset that a pipe can withstand by at least 20%, which is more effective than other conventional techniques, such as replacing native soils with loosely compacted soils, upgrading the pipe class, increasing the pipe wall thickness, and reducing the burial depth. Design implications of enlarging the trench and aligning the pipe at a fault-pipe crossing angle of 90° are recommended for improving the mitigation efficiency.