Liquefaction Resistance of Sand Improved with Enzymatically Induced Calcite Precipitation based on Laboratory Investigation

Abstract

Liquefaction possibility assessment of soil in field is a prominent aspect on geotechnical engineering practice. Varieties of evaluations have been developed including penetration-based methods and shear wave velocity methods over the years since Seed & Idriss (1971) introduced the simplified method based on SPT data. With the focus on natural soil, those methods have been well evolved and have become the most frequent techniques used for evaluating liquefaction possibility of soil in situ. However, the capability of those empirical relations for evaluating liquefaction possibility of ground improved with EICP approach needs authentication. This research presents the capability of the available liquefaction evaluation charts for evaluating liquefaction possibility of ground improved with EICP approach. Investigations were conducted using cyclic triaxial apparatus integrated with bender element to evaluate liquefaction resistance, RL , of EICP-improved sand as a liquefaction countermeasure. Parameters used were confining pressures, degrees of saturation during curing, calcite contents, and particles size of the sand. The test results were compared with the field performance charts of natural soils introduced by investigators. The results show that slight amount of the precipitated calcite can improve notably the maximum shear modulus of soils directly associating to Vs improvement. The correlation between corrected resistance to liquefaction CRR (cyclic resistance ratio) and adjusted shear wave velocity Vs1 of EICP-improved sands, CRR-Vs1 correlation, tends to represent different tendency with that of unimproved sands. It appears that available liquefaction prediction curves are not capable for evaluating liquefaction possibility of EICP-improved ground.