青海强盐渍粉砂土MICP的有效性探索

在极端环境中发现原生高产脲酶微生物并开展岩土体的固强研究，是岩土体微生物矿化研究的一个热点和难点。该文在青海柴达木地区的强盐渍土中发现一种新型原生高产脲酶微生物，在强盐环境中，试验该微生物的盐耐受性和矿化性能，开展被加固土体力学强度试验。结果表明：在强盐渍环境下，该新型微生物脲酶活性保持在3.02U～5.03U。在强盐渍粉砂土中进行微生物矿化试验，一周时间内，可以使盐渍粉砂土柱中的碳酸钙含量增加8.11%，碳酸钙主要以球霰石为主；土柱的孔隙率降低6.12%，孔径由4～40μm大孔隙为主，变为以0.4～4μm的中孔隙为主，孔径分布范围变小了65%～68%；土柱的基本力学强度指标值得到提升。研究表明：该新型原生高产脲酶微生物对青海强盐渍土环境具有良好的耐受性，经过对其矿化诱导，可以产生球霰石沉淀，并能有效地黏结盐渍土颗粒，实现对盐渍土固强的目的。研究提供了在强盐渍土中进行微生物提取和矿化固强的研究方法，为探索高盐极端环境岩土材料MICP的有效性，提供一种新思路。

Study on the effectiveness of MICP for highly saline silty soil in Qinghai

It is a focus and difficult issue in the research of microbial mineralization to discover and utilize natural urease-producing microorganisms for solidification and strengthening of rocks and soils in extreme environments. In this work, a new and natural microorganism of generous urease discovered in highly saline land of Qaidam region in Qinghai province has been experimentally studied on its salt tolerance, mineralization as well as solidification and strengthening of soils. The research results show that the urease activity of the microorganism is maintained between 3.02 U and 5.03 U, accounting for excellent survivability of the microorganism in highly saline soil. Then, after one week of microbial mineralization, solidification and strengthening of highly saline soil, the mechanical strength experiments of soil column are carried out. The averages of results indicate that: the calcium carbonate (mainly consisting of vaterite crystals) content in columns may be increased by 8.11%; the porosity of soil columns may be decreased by 6.12% and the pore size changes from large pores of 4～40 μm to medium pores of 0.4～4 μm, and the pore size distribution range is reduced by 65 to 68 percent; several parameters of basic mechanical strength are improved. The research data indicate that the new microorganism has good tolerance to the highly saline soil in Qinghai and the precipitation of vaterite crystals after microbially induced mineralization can effectively cement the soil particles and enhance the strength of soil. The research provides a method for microbial extraction and mineralized solidification in saline soil, which can be used to explore the effectiveness of microbially induced carbonate precipitation (MICP) in extreme environments.