Centrifuge modelling of remediation of liquefaction-induced pipeline uplift using root systems

Buried pipelines are susceptible to floatation within liquefiable soil after earthquakes. When soil liquefies, its shear strength is significantly reduced due to generation of excess pore pressure. A buried pipeline within such soil can then uplift due to a combination of (i) an upwards pore pressure gradient across the pipe and (ii) the resisting force contributed from soil shear strength being significantly reduced. Roots have been confirmed to increase the shear resistance of soil, so they can potentially be used as a new countermeasure against pipeline uplift, in locations where there is no above-ground infrastructure (i.e. where uplift is most likely). Three centri-fuge tests have been conducted in this study to evaluate this potential. One was performed as a benchmark and the other two included one of two overlying model shallow root systems (either fibrous roots only, or fi-brous and large structural roots) respectively. The results show that roots can be used as a remediation method against pipeline uplift induced by soil liquefaction. Model fibrous roots were shown to reduce uplift displace-ments by 15% while the model system consisting of both large structural and fibrous roots further reduced up-lift to approximately 28%.