Microbially induced calcite precipitation (MICP) technique has gained attention recently as a novel method to enhance the engineering properties of soils, especially sandy soils. However, the applicability of this method to field scale is challenging and requires understanding of the factors affecting MICP process under variable subsurface conditions. This study presents a laboratory investigation and numerical predictive model to assess pore-water chemistry and calcite precipitation during the biocementation process. Laboratory experiments were conducted to assess the microbial treatment of Narmada sand in plastic tubes using three bacterial strains and two cementation media concentrations. Calcite precipitation via ureolysis as a result of biogeochemical reactions was measured. The effects of pH and electrical conductivity (EC) on the rate of urea hydrolysis and calcite precipitation were assessed. The presence of calcite crystals was analyzed using scanning electron microscopy (SEM). The SEM images confirmed the formation of calcite at the surface and between the sand particles. A simplified numerical model was developed to estimate the rate of urea hydrolysis and their effects on the biocementation of sand. Three stages of MICP process were identified: bacterial ureolysis, dynamic equilibrium between liquid-gas interface and oversaturation of ions, and calcite precipitation. The variations of pH and EC at these three stages were modeled. The predicted pH, EC, and calcite precipitation based on the simplified model were found to be in close agreement with the experimental results. The numerical model can be used to assess and optimize the system variables for effective MICP field applications.

微生物诱导方解石沉淀（MICP）技术作为提高土壤，特别是沙质土壤的工程性能的一种新方法最近已受到关注。但是，该方法在油田规模上的适用性具有挑战性，并且需要了解在可变的地下条件下影响MICP过程的因素。这项研究提出了一个实验室调查和数值预测模型，以评估生物胶结过程中的孔隙水化学和方解石沉淀。进行了实验室实验，以评估使用三种细菌菌株和两种胶结介质浓度对塑料管中的纳尔默达沙进行微生物处理的情况。测量了由于生物地球化学反应而经尿素分解产生的方解石沉淀。评估了pH和电导率（EC）对尿素水解和方解石沉淀速率的影响。使用扫描电子显微镜（SEM）分析了方解石晶体的存在。SEM图像证实了在表面和沙粒之间的方解石形成。开发了一个简化的数值模型来估计尿素水解的速率及其对沙子生物胶结的影响。确定了MICP过程的三个阶段：细菌尿解，液-气界面与离子过饱和之间的动态平衡以及方解石沉淀。对这三个阶段的pH和EC的变化进行了建模。发现基于简化模型的预测pH，EC和方解石沉淀与实验结果非常吻合。