冻融循环条件下MICP技术自修复能力研究

    STUDY OF SELF-HEALING CAPABILITY OF MICP TECHNOLOGY UNDER FREEZE-THAW CYCLE CONDITIONS

    • 摘要: 微生物诱导碳酸钙沉淀(MICP)技术可有效固化重金属污染土,复杂的外界环境会影响固化土的耐久性。本文通过开展无侧限抗压强度试验与细菌活性试验,重点研究了冻融循环作用对MICP固化铅污染土强度特性及自修复能力的影响,揭示了强度与自修复能力之间的关系及微观作用机理。试验结果表明:随着冻融循环次数的增加,土体的高度与直径有所增大,但未产生裂隙,土体的无侧限抗压强度逐渐降低并趋于稳定;10次冻融循环作用后,巴氏芽孢杆菌仍具有一定的自修复能力,可继续固化土体,但活性较低。冻融循环过程中,巴氏芽孢杆菌可通过自修复再次产生碳酸钙沉淀,弥补一部分的强度损失,使得土体的无侧限抗压强度损失率较小。

       

      Abstract: Microbially induced calcite precipitation(MICP)technology can effectively solidify heavy metal-contaminated soils,and the complex external environment can affect the durability of the cured soil. In this paper,by conducting unconfined compressive strength tests and bacterial activity tests,we focused on the effects of freeze-thaw cycling on the strength characteristics and self-healing capacity of MICP-solidified lead-contaminated soil,revealing the relationship between strength,self-healing capacity,and the microscopic mechanism of action. The test results showed that with the increase of freeze-thaw cycles,the height and diameter of the soil increased,but no fissures were produced,and the unconfined compressive strength of the soil gradually decreased and stabilized. After 10 freeze-thaw cycles,Bacillus still had a certain self-healing ability and could continue to solidify the soil,although the activity was low. During the freeze-thaw cycle,Sporosarcina pasteurii can produce calcium carbonate precipitation again through self-healing to make up for part of the strength loss,which results in a smaller unconfined compressive strength loss rate of the soil body.

       

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