Buoyancy of Buried Pipes in Liquefiable Soil under Rooting

Abstract

A total of sixteen shaking test were conducted to determine the effectiveness of polypropylene fibre reinforcement in hindering the vertical displacement of a buoyant object in liquefied sand. By comparing the measured ascension velocity of the buoyant object in different tests the sample yielding the most desirable results was identified. While completely restraining the buoyant object proved impossible, ascension velocities of up to eighteen times lower were recorded in reinforced sand layers compared to that in average clean sand. Analysis of test results shows that, when initially coming into contact with the fibre-reinforced sand layer, the buoyant object’s ascension velocity is only mildly affected, but begins to decrease significantly after the layer has been penetrated to a certain degree. It has been found that this is due to the fact that a driving shear force is needed to activate the strain-hardening response of the fibre reinforced sand layer. Fibre reinforcement may thus become a mitigation method to minimize liquefaction-caused damage to infrastructural lifeline networks.