
Soil Liquefaction Considerations at Burrard Inlet, False Creek, and the Fraser River
Liquefaction is the process by which the soil sediments below the water table temporarily lose Its strength due to the application of earthquake-induced cyclic shear stresses, and behave as a viscous liquid rather than soil (1). Liquefaction phenomenon can lead to slope instability, lateral spreading of ground, settlement, increased lateral loads on retaining walls and piles, and loss of foundation support.
Liquefaction and lateral spreading for Jetty Foundation
Liquefaction and lateral spreading for Jetty Foundation

In the case of the jetty foundation, liquefaction induced by seismic activity may cause uncontrolled or differential settlement and temporary loss of bearing capacity. To investigate the risk of any of these mechanisms to affect the stability of the jetty and its foundation, a liquefaction potential (LP) analysis of the soil is carried out according to the seismic events as outlined in Canadian Highway Bridge Design Code. The LP of a soil is defined as the ratio between the Cyclic Resistance Ratio CRR (the capacity of the soil to resist liquefaction) and the Cyclic Stress Ratio CSR (the seismic demand on a soil layer). A commonly used safety factor worldwide for this susceptibility ratio is 1.2.