Experimental Investigation of Biological Injection for Enhancing Bearing Capacity of gravel Columns

From the past to the present, the construction of structures on soft and weak soils has consistently posed challenges for geotechnical engineers, requiring the improvement of soil properties. Specifically, foundations for structures built on tailings or weak soils in mining areas require stabilization and improvement. Among various methods for soil improvement, the injection of chemical and biological materials stands out. The injection of chemicals like cement and lime, while effective, is often costly and can have toxic effects. Recently, the process of microbial-induced calcite precipitation (MICP) has emerged as a widely used, environmentally friendly technology for soil stabilization. Several factors, including temperature, pH, injection method, and reactant concentration, influence the MICP process. Based on previous studies, optimal limits for each of these factors have been established to achieve the best results. This study specifically investigates the effect of the MICP process on the bearing capacity of sand columns. These columns are commonly used to stabilize soft soils, particularly for foundations that require reinforcement, such as those used in mining operations. In this study, Bacillus pasteurii was used as the bacterium for the MICP process, and the soil investigated consisted of high-plasticity clay and fine sand. The treatment was applied to the sand columns. The results indicated that the MICP process significantly increased the bearing capacity and reduced settlement. The bearing capacity of the treated sample was 4.3 times greater than that of the untreated sample, indicating that calcite precipitation helps bind soil particles together …