Hu Jun, Fan Fei, Huang Luyan, Yu Junchao
School of Civil Engineering and Architecture, Hainan University, Haikou 570228, China.
Collaborative Innovation Center of Marine Science and Technology, Hainan University, Haikou 570228, China.
Materials (Basel). 2024 May 15;17(10):2362. doi: 10.3390/ma17102362.
Currently, coastal sandy soils face issues such as insufficient foundation strength, which has become one of the crucial factors constraining urban development. Geotechnical engineering, as a traditional discipline, breaks down disciplinary barriers, promotes interdisciplinary integration, and realizes the green ecological and low-carbon development of geotechnical engineering, which is highly important. Based on the "dual carbon" concept advocating a green and environmentally friendly lifestyle, Bacillus spores were utilized to induce calcium carbonate precipitation technology (MICP) to solidify coastal sandy soils, leveraging the rough-surface and low-permeability characteristics of silty soil. The mechanical-strength variations in the samples were explored through experiments, such as calcium carbonate generation rate tests, non-consolidated undrained triaxial shear tests, and scanning electron microscopy (SEM) experiments, to investigate the MICP solidification mechanism. The results indicate that by incorporating silty soil into sandy soil for MICP solidification, the calcium carbonate generation rates of the samples were significantly increased. With the increase in the silty-soil content, the enhancement range was 0.58-3.62%, with the maximum calcium carbonate generation rate occurring at a 5% content level. As the silty-soil content gradually increased from 1% to 5%, the peak deviator stress increased by 4.2-43.2%, enhancing the sample shear strength. Furthermore, the relationship between the internal-friction angle, cohesion, and shear strength further validates the enhancement of the shear strength. Silty soil plays roles in adsorption and physical filling during the MICP solidification process, reducing the inter-particle pores in sandy soil, increasing the compactness, providing adsorption sites, and enhancing the calcium carbonate generation rate, thereby improving the shear strength. The research findings can provide guidance for reinforcing poor coastal sandy-soil foundations in various regions.
目前，沿海砂土面临地基强度不足等问题，已成为制约城市发展的关键因素之一。岩土工程作为一门传统学科，打破学科壁垒，促进学科交叉融合，实现岩土工程绿色生态低碳发展，具有重要意义。基于倡导绿色环保生活方式的“双碳”理念，利用芽孢杆菌诱导碳酸钙沉淀技术（微生物诱导碳酸钙沉淀技术，MICP），借助粉质土表面粗糙、渗透性低的特点来固化沿海砂土。通过碳酸钙生成率试验、不固结不排水三轴剪切试验和扫描电子显微镜（SEM）试验等实验，探究样品的力学强度变化，以研究MICP固化机理。结果表明，通过将粉质土掺入砂土进行MICP固化，样品的碳酸钙生成率显著提高。随着粉质土含量的增加，提高幅度为0.58 - 3.62%，碳酸钙生成率在含量为5%时达到最大值。当粉质土含量从1%逐渐增加到5%时，峰值偏应力增加了4.2 - 43.2%，提高了样品的抗剪强度。此外，内摩擦角、黏聚力与抗剪强度之间的关系进一步验证了抗剪强度的提高。粉质土在MICP固化过程中起到吸附和物理填充作用，减少砂土颗粒间孔隙，增加密实度，提供吸附位点，提高碳酸钙生成率，从而提高抗剪强度。研究结果可为各地加固不良沿海砂土路基提供指导。
