Microbial-induced calcite precipitation (MICP) is an emerging ground treatment technique in geotechnical engineering. This technique is performed through injecting bacteria into the soil and then hydrolyzing urea into carbanion to induce the calcite crystals at the presence of calcium ions. Accordingly

the precipitated calcite crystals are used to bond loose soil particles together. Distribution uniformity of calcite crystals is a key point for this technique. In this study

calcium chloride solution with a concentration of 0.05 mol/L is introduced into the pure bacteria solution to intervene in the distribution of bacteria

the effects of biological injection methods

i.e. the pure/mixed bacteria solution

the mixed bacteria solution and the traditional pure bacteria solution on the dynamic behavior of bio-cemented sand are analyzed by dynamic triaxial test and scanning electron microscope (SEM) test. The test results indicate that the pure/mixed bacteria solution can effectively improve the distribution uniformity of calcite crystals in bio-cemented sand

obtaining bio-cemented sand with higher content of calcite

greater dynamic modulus and energy-dissipating capacity.