Abstract

As a novel, nature-like biomineralization process, microbially induced carbonate precipitation (MICP) has been successfully applied in soil stabilization. This study investigated the influence of biomass injected on the geotechnical performance of MICP treated sand. Grouting rate and particle sizes were also taken into account. The results showed that the injection of 1.0 or 1.2 PV biological solution achieved the most effective and uniform reinforcement of soil, depending on the grouting rate. Excessive biomass (1.5 PV biological solution) failed to promote the further improvement of the engineering performance of MICP reinforced sand. The relationship between strength and calcium carbonate content and SEM results indicated that for the small CaCO₃ content, the improvement of soil strength is mainly controlled by the content of calcium carbonate rather than its distribution. When the amount of carbonate precipitation is sufficient to form bonding between soil particles, the distribution of calcium carbonate has a greater influence on mechanical properties. The strength of biocemented soil measured by layering indicated that the insufficient amount of biological solution (such as 0.5 PV biological solution) greatly weakened the reinforcement effect of soil away from the grouting port, and thus led to larger strength variability. Increasing the grouting rate of biological solution improved the uniformity of reinforcement, especially for medium grain sand. The results of this study provide a guide to facilitate the application of microorganisms in the engineering application practice of MICP.

摘要

微生物诱导碳酸盐沉淀（MICP）作为一种新颖的、类自然的生物矿化过程，已成功应用于土壤稳定。本研究调查了注入的生物质对 MICP 处理砂岩土工性能的影响。还考虑了注浆速率和粒度。结果表明，根据注浆速率，注入 1.0 或 1.2 PV 生物溶液可实现最有效和均匀的土壤加固。过量的生物质（1.5 PV生物溶液）未能促进MICP加筋砂工程性能的进一步提高。强度与碳酸钙含量的关系和SEM结果表明，对于小CaCO ₃含量，土体强度的提高主要受碳酸钙含量而不是其分布控制。当碳酸盐沉淀量足以形成土壤颗粒之间的结合时，碳酸钙的分布对力学性质的影响更大。分层测量的生物胶结土强度表明，生物溶液（如0.5PV生物溶液）用量不足，大大削弱了远离注浆口的土壤的加固作用，从而导致强度变异较大。提高生物溶液的注浆率，提高了加筋的均匀性，特别是对中粒砂。本研究结果为促进微生物在MICP工程应用实践中的应用提供了指导。