| The ground improvement industry exceeds ;Treasure Island in San Francisco, California was chosen as an idealized site to compare five different ground improvement methods; (deep soil mixing, vibro replacement, vibro compaction, deep dynamic compaction, and earthquake drains). All were compared on the basis of a functional unit of treating 25,000 cubic meters (50 m x 50 m x 10 m) of loose, sandy hydraulic fill. Each method was required to meet a performance specification of SPT blow counts over 15 in order to mitigate liquefaction potential.;Deep soil mixing was the most impactful method, mainly due to the use of portland cement. Introduction of slag cement reduced greenhouse gas emissions to nearly a quarter of the conventional method. Outcomes for all other methods were heavily dependent on transportation of materials and mobilization. The redevelopment of Treasure Island was used as an idealized site scenario for the purpose of comparing multiple ground improvement scenarios. These scenarios were combinations of ground improvement methods that would be realistic choices for when Treasure Island is redeveloped. At the site level, considering the actual soil conditions, a combination of vibro replacement, deep dynamic compaction, and vibro compaction resulted in the lowest environmental impact based on greenhouse gas emissions and life cycle energy. |
