An evaluation of the liquefaction potential of the Fraser Delta

Abstract

Empirical and analytical methods for predicting the occurrence of liquefaction of foundation soils during an earthquake are examined and applied to the Fraser Delta area of British Columbia. The area is diked and at present has a population of about 150 000 people who reside mainly in low-rise buildings. Liquefaction of the foundation soils would cause severe damage to buildings, services, highway and railway links, and the dikes.Application of empirical methods based on blow count values indicates that liquefaction of the foundation soils could occur. Application of analytical methods indicates that liquefaction could occur in the event of an earthquake having a maximum ground surface acceleration of 0.12g (the 100 year value).The effects of various remedial measures are examined and it is shown that densification, drainage, and fill loading serve to reduce the tendency for liquefaction to occur. The presence of a low permeability layer close to the surface may cause liquefaction to occur by impeding the drainage.Construction that involves placing large sand fills with adequate drainage through the surficial low permeability layer to support low rise buildings would seem to be the least hazardous for this region.