Abstract Enzyme-induced carbonate precipitation (EICP) is an innovative bio-inspired approach that has emerged in recent years, offering a more environmentally sustainable option for soil improvement. The present article aims at extensively examining the effect of EICP treatment on the cyclic response of silty sands containing petroleum hydrocarbon compounds. Strain-controlled cyclic triaxial tests have been carried out on hydrocarbon contaminated sand with and without EICP treatment. Several independent variables such as hydrocarbon content (2, 4, 6, 8, and 10%), shear strain amplitudes (0.5% and 1%), and curing period (7 days and 14 days) were considered in the study. Prior to this, a baseline analysis was conducted to determine the effect of EICP treatment solution composition on the efficiency of carbonate precipitation. The effectiveness of the treatment was systematically investigated based on cyclic pore pressure response and degradation of cyclic shear modulus. The results revealed that petroleum contamination moderately increases the cyclic resistance up to a transition point beyond which it falls off sharply. The coupled effect of increasing oil content and curing time of EICP treatment has also been assessed. The variation of cyclic strength with crude oil content results in a single-peaked profile for both untreated and treated specimens. EICP treatment increases the cyclic resistance of oil-contaminated sand up to 1.5 times by suppressing the excess pore pressure build-up. A signification recovery in the degradation parameter, as high as 80%, was also observed. However, with increasing oil content and shear strain levels, the efficacy of EICP treatment exhibited a remarkable decline. The microstructural mechanism believed to be responsible for such a behavior has also been discussed.

中文翻译：

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EICP 处理碳氢化合物污染砂岩的循环降解和孔隙压力动力学

摘要 酶诱导碳酸盐沉淀 (EICP) 是近年来出现的一种创新的生物启发方法，为土壤改良提供了更环保的可持续选择。本文旨在广泛研究 EICP 处理对含有石油烃化合物的粉砂岩循环响应的影响。应变控制循环三轴试验已经在有和没有 EICP 处理的碳氢化合物污染的沙子上进行。研究中考虑了几个独立变量，例如碳氢化合物含量（2、4、6、8 和 10%）、剪切应变幅度（0.5% 和 1%）和固化期（7 天和 14 天）。在此之前，进行基线分析以确定 EICP 处理溶液组成对碳酸盐沉淀效率的影响。基于循环孔隙压力响应和循环剪切模量的退化，系统地研究了处理的有效性。结果表明，石油污染会适度增加循环阻力，直至达到一个过渡点，超过该过渡点它会急剧下降。还评估了增加油含量和 EICP 处理固化时间的耦合效应。循环强度随原油含量的变化导致未处理和处理样品的单峰分布。EICP 处理通过抑制超孔隙压力的增加，将油污染砂的循环阻力提高了 1.5 倍。还观察到降解参数的显着恢复，高达 80%。然而，随着含油量和剪切应变水平的增加，EICP 治疗的疗效显着下降。还讨论了被认为是造成这种行为的微观结构机制。