Abstract:
At a project site in San Diego, California, the hazards of liquefaction, seismically-induced settlement, and lateral spreading were all present at a site, in conjunction with soils that would require a low bearing value for use of spread footings. In addition, the site had variable conditions such that a portion of the site did not exhibit such hazards. Therefore, vibro-replacement stone column ground improvement was chosen to be performed such that the multiple hazards would be mitigated, allowing for use of spread footing foundations throughout the site for a new building development. The post-improvement seismic performance of the soils beneath footings was calculated and served as the basis for seismic design for the vibro-stone columns. The post-improvement static performance of the soils beneath footings was tested using “ modulus tests” in the field. The results of the modulus tests confirmed the design assumptions regarding static settlement. The construction techniques are discussed herein, and the testing and calculations used to justify the mitigated hazards and design criteria.