Cheng Yaojia, Tang Chaosheng, Xie Yuehan, et al. 2021. Experimental study on structure strength of loess improved by microbial induced calcite precipitation [J]. Journal of Engineering Geology, 29(1): 44-51. doi: 10.13544/j.cnki.jeg.2020-359.
    Citation: Cheng Yaojia, Tang Chaosheng, Xie Yuehan, et al. 2021. Experimental study on structure strength of loess improved by microbial induced calcite precipitation [J]. Journal of Engineering Geology, 29(1): 44-51. doi: 10.13544/j.cnki.jeg.2020-359.

    EXPERIMENTAL STUDY ON STRUCTURE STRENGTH OF LOESS IMPROVED BY MICROBIAL INDUCED CALCITE PRECIPITATION

    • Soil erosion and geological disasters in loess area of China are extremely serious, which is mainly related to the poor engineering geological properties of loess. Microbial induced calcium carbonate precipitation(MICP)was used in order to improve the mechanical behavior of loess. We sprayed the prepared bacterial solution and cementation solution to the surface of the soil sample for MICP treatment. Based on the penetration test and calcium carbonate content test, we analysed the influence of MICP-treated cycles(3, 5, 7 rounds) and cementation solution concentrations(0.5 M, 1 M, 5 M)on penetration strength and calcium carbonate content of MICP-treated samples. The results show that: (1)MICP technology can significantly improve the structure strength and form a hard crust with high strength on the surface of soil sample. (2)With the increase of MICP treatment cycles, the strength and thickness of hard crust, internal strength of soil and the content of calcium carbonate increase gradually. (3)The concentration of cementing solution has a significant influence. The sample treated by 1.5 M cementing solution performs the best treatment effect with structure strength of surface up to 600 kPa and good internal integrity. The effect of the sample treated by 1.5 M cementing solution is worse than 1.0 M. A thin hard crust is formed on the surface of it and the internal strength of it is low. The mechanical strength of soil sample treated by 0.5 M cementing solution is improved insignificantly. (4)The mechanism of MICP improvement on the structure strength of loess is mainly that calcium carbonate induced by microorganisms cements soil particles, which greatly improves the connection strength between soil particles and significantly improves the mechanical properties of soil.
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