Microbially induced calcite precipitation (MICP) is a bioinspired improvement method of granular soils, as it can significantly affect their engineering characteristics. In fact, calcite nanoparticles produced through MICP increase the angle of internal friction and cohesion intercept of granular soils. As a consequence, the shear strength values of granular soils are improved following the increase in these two parameters. However, MICP is not very efficient in strengthening fine-grained soils. In this study, using Sporosarcina pasteurii for MICP treatment, the effects of biocementation and plastic and non-plastic fines (clay and silt) on the shear strength parameters of sandy soils were investigated after 7, 10 and 15 d of treatment to analyse the viability of MICP in different sand mixtures in the field. Direct-shear tests, X-ray diffraction and scanning electron microscopy were used as investigative tools. The results obtained in this study showed that there was a significant improvement in the shear strength of the samples, while noticeable modification occurred within the first 7 d of treatment and fines reduced the MICP potential for strengthening of sandy soils. Although MICP boosted the cohesion intercept and the angle of internal friction of the samples, a great amount of the gained strength was due to cohesion growth.

中文翻译：

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生物胶结对粉质砂质黏土强度参数的影响

微生物诱导的方解石沉淀（MICP）是一种生物启发的颗粒状土壤改良方法，因为它会显着影响其工程特性。实际上，通过MICP生产的方解石纳米颗粒会增加颗粒状土壤的内部摩擦和内聚力拦截角度。结果，随着这两个参数的增加，粒状土壤的抗剪强度值得到改善。但是，MICP在强化细粒土壤方面不是很有效。在这项研究中，使用孢子菌在进行MICP处理时，研究了生物胶结物以及塑料和非塑料细料（粘土和粉砂）对砂土在7、10和15 d处理后的抗剪强度参数的影响，以分析MICP在不同砂混合物中的活力。场。直接剪切试验，X射线衍射和扫描电子显微镜被用作研究工具。这项研究获得的结果表明，样品的剪切强度有了显着提高，而在处理的前7 d内发生了明显的变化，而细粉降低了MICP增强砂土的潜力。尽管MICP增强了样品的内聚力拦截力和内摩擦角，但由于内聚力的增长，获得的大量强度得到了提高。