Tiwari Nitin, Satyam Neelima, Sharma Meghna
Department of Civil Engineering, Indian Institute of Technology Indore, Indore, India.
Sci Rep. 2021 May 14;11(1):10324. doi: 10.1038/s41598-021-89687-2.
This study explored the effect of indigenous bacteria present in the soil to stabilized swelling behavior and improving the mechanical property of expansive soil. The objective of the research is to investigate the effectiveness of the biostimulation microbial induced calcite precipitation (MICP) for controlling the swelling-shrinkage behavior and improving shear strength of expansive soil. An attempt was made to develop an effective procedure to culture the indigenous bacteria for treating clays with varying plasticity and improve their engineering behavior. The detailed procedure has been investigated to effectively apply the MICP technique in clay soil, considering its low permeable nature. The applicability of biostimulation to clayey soils in minimizing their swelling potential and improving the strength is assessed. Both macroscale and microscale studies were conducted on untreated and biostimulated soils to observe changes in plasticity, strength, swelling, mineralogical, chemical characteristics. The present method has shown an effective alternative to improve the road pavement subgrade without affecting the eco-system of natural soil. The method investigated the effective way of providing the enrichment and cementation solution in clayey soil, which is the major concern in current literature. The study confirms that the calcite content has been increased with biostimulated MICP treatment up to 205% in the treated specimens and which future increased the unconfined compressive strength and split tensile strength. A reduction in the swelling pressure and swell strain is also observed. The results show that a cost-effect and eco-friendly method can be deployed for stabilizing the road pavement subgrades. The statistical assessment using multivariate analysis and hierarchical clustering dendrogram has been carried out to investigate the effect of the MICP treatment protocol on different soil and engineering parameters.
本研究探讨了土壤中存在的原生细菌对稳定膨胀行为及改善膨胀土力学性能的影响。该研究的目的是调查生物刺激微生物诱导碳酸钙沉淀（MICP）在控制膨胀土胀缩行为及提高其抗剪强度方面的有效性。尝试开发一种有效的程序来培养原生细菌，以处理不同塑性的黏土并改善其工程性能。考虑到黏土的低渗透性，已对有效应用MICP技术于黏土中的详细程序进行了研究。评估了生物刺激在降低黏性土膨胀潜力及提高强度方面的适用性。对未处理和经生物刺激的土壤进行了宏观和微观研究，以观察其塑性、强度、膨胀、矿物学和化学特性的变化。本方法已显示出一种有效的替代方案，可在不影响天然土壤生态系统的情况下改善道路路面路基。该方法研究了在黏性土中提供富集和胶结溶液的有效方式，这是当前文献中的主要关注点。研究证实，经生物刺激的MICP处理后，处理后试样中的方解石含量增加了205%，这进而提高了无侧限抗压强度和劈裂抗拉强度。还观察到膨胀压力和膨胀应变有所降低。结果表明，可以采用一种经济高效且环保的方法来稳定道路路面路基。已进行了使用多变量分析和层次聚类树状图的统计评估，以研究MICP处理方案对不同土壤和工程参数的影响。
