Abstract: Microbial grouting reinforcement technology is a newly developed soil reinforcement method in recent years, which has excellent effects on the reinforcement of tailings ponds and greatly reduces the risk of tailings dam failure. Due to uneven grouting, the development of this technology in practical applications is relatively slow. At present, the commonly used methods for microbial reinforcement technology in the laboratory are unidirectional grouting and bidirectional grouting, both of which have the problem of uneven solidification. To improve the uniformity of microbial reinforcement of soil, this paper proposes a cross bidirectional grouting method while controlling the grouting rate. Cross grouting allows bacterial liquid and cementitious liquid to enter the soil from both ends of the biological column, solidifying the middle part of the biological column. Bidirectional grouting allows bacterial liquid and cementitious liquid to enter the soil from the same end of the biological column, solidifying both ends of the biological column. It was shown that under the same grouting conditions, the unconfined compressive strength of specimens prepared by the cross bidirectional grouting method increased by 329 kPa compared to that of specimens prepared by the bidirectional grouting method, and the calcium carbonate mass fraction in the middle part of the sand column increased from 18.98% to 22.08%. During the cross bidirectional grouting process, the unconfined compressive strength of the sand column reached a maximum value of 1211 kPa at the injection rates of 1.2 mL/min for bacterial liquid and 1.4 mL/min for cementitious liquid, respectively. At the same time, the calcium carbonate mass fraction in the middle part of the sand column increased by 2.18% to 1.85%, and the calcium carbonate mass fraction in the middle part of the sediment was reduced by 1.52% to 1.38%. These results indicate that the cross bidirectional grouting method can effectively improve the performance of microbial reinforcement in the reinforcement of tailings ponds and greatly reduce the risk of tailings dam failure. bonate mass fraction in the middle part of the sand column also increased to 24.31%.
Keywords: microbially induced calcite precipitation (MICP); tailings sand; cross grouting; bidirectional grouting; unconfined compressive strength; calcium carbonate mass fraction
合肥工业大学学报自科版