Dynamic strength of temperature-controlled MICP-treated calcareous sand

A series of undrained cyclic triaxial tests are carried out for calcareous sand treated by temperature-controlled MICP (microbially induced calcium carbonate precipitation) technology, and the dynamic strength characteristics of MICP-treated calcareous sand are thoroughly investigated. The in-depth discussion is conducted for the effects of biocementation level, relative density and effective confining pressure on dynamic strength and liquefaction characteristics. The dynamic and liquefaction characteristics of loose calcareous sand gradually change from flow slide to cyclic mobility after MICP treatment. Compared with the untreated medium dense calcareous sand, the MICP-treated medium dense calcareous sand shows more obvious characteristics of cyclic mobility. An increase in biocementation level, relative density and effective confining pressure leads to an increase in the dynamic strength of MICP-treated calcareous sand in different extents. Based on the optimized empirical formula of dynamic strength for MICP-treated calcareous sand, a uniform dynamic strength criterion is further established for MICP-treated calcareous sand. The unified dynamic strength criterion in this study will provide an important theoretical basis for the development and application of MICP treatment technology in the construction of islands and reefs in South China Sea.