多浓度营养盐处理对微生物胶结砂土均匀性与强度的影响

采用二次注入菌液方式,制备不同浓度营养盐处理的MICP(微生物诱导碳酸钙沉淀)胶结砂样。选用巴氏芽孢杆菌作为固化细菌,采用单一浓度(0.5、1.0mol/L)和多浓度相结合(前期采用0.5mol/L,后期采用1.0mol/L)的处理方式注射营养盐(尿素/氯化钙混合液),研究多浓度营养盐结合处理方式对微生物固化砂土强度及均匀性的影响。基于试验测试分析了固化砂土试样不同区间段的强度、弹性模量以及碳酸钙含量。试验结果表明,多浓度营养盐处理方式对固化砂土试样的强度及碳酸钙含量有明显影响;多浓度营养盐结合处理方式能够保证试样有较好的均匀性条件下获得较高强度及弹性模量。基于多浓度营养盐处理方式,探讨分析了影响试样强度和均匀性的基本因素。

Effects of multi-nutrient treatment on the uniformity and strength of MICP-cemented sand

The MICP(microbial induction of calcium carbonate precipitation)cemented sand samples are prepared by injecting twice bacteria solution with different concentrations of nutrient salt treatment. S. pasteurii is used to induce calcite precipitation, and all the specimens were prepared by injecting a single concentration or multi-concentration nutrient solutions. In this study, 0.5 and 1.0 mol/L urea-calcium chloride solutions are used for the former grouting treatment, while for the latter one, 0.5 mol/L urea-calcium chloride solution is firstly injected; and subsequently, 1.0 mol/L urea-calcium chloride solution is utilized. Based on the experiment, the strength, modulus of elasticity and calcite content of MICP specimens'' different sections are analyzed. From the experimental results, it can be found that multi-concentration nutrient treatment has significant influence on the unconfined compressive strength of bio-cemented sand and calcite content. The multi-concentration nutrient treatment can ensure the high strength and elastic modulus of the sample under the condition of good uniformity. Finally, the basic factors that affect the strength and uniformity of samples were discussed based on the method of multi-concentration nutrient treatment.