关键词: 微生物固化砂土, 菌液注射方式, 动三轴试验, 扫描电镜测试

Abstract: 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.

Key words: bio-cemented sand, biological injection method, dynamic triaxial test, scanning electron microscope test