微生物加固黏土的影响因素与机理分析

为了在岩土和环境工程中更好推广应用微生物诱导碳酸钙沉淀加固技术,本文开展了微生物加固黏土的试验研究,分析了微生物加固黏土试验的主要影响因素,并通过宏观试验结合微观分析的方法研究其加固机理。试验结果表明:适宜的培养基、接种比例和培养环境(温度、pH值)有利于微生物的生长繁殖;在一定脲酶活性条件下,养护温度、养护时间、胶结液的浓度和比例均对微生物诱导碳酸钙的生成量影响显著;碳酸钙的生成量直接影响微生物加固黏土的加固效果,微生物加固黏土的无侧限抗压强度与碳酸钙生成量成正相关,其养护7d的无侧限抗压强度可提高50%以上,破坏应变可降低约70%;微生物加固黏土表面形成大量晶体,实现了土颗粒间的胶结,填充了颗粒间的孔隙,增加了黏聚力和内摩擦角,从而提高了土体强度。

Analysis of influencing factors and mechanism of microbial clay reinforcement

In order to better promote the application of microbial induced calcium carbonate precipitation reinforcement technology in geotechnical and environmental engineering,this paper carried out experimental research on microbial solidified clay, analyzed the main influencing factors of the microbial solidified clay test,and studied its reinforcement mechanism by means of macroscopic test combined with microscopic analysis. The results showed that the suitable culture medium, inoculation ratio and culture environment (temperature,pH value) were beneficial to the growth and reproduction of microorganisms. Under certain urease activity,the curing temperature,curing time,the concentration and proportion of the cementing solution all had significant influence on the microbial induced calcium carbonate production. The amount of calcium carbonate directly affects the reinforcement effect of the clay reinforced by microorganisms. The unconfined compressive strength of the clay is positively correlated with the amount of calcium carbonate. The unconfined compressive strength of the clay after curing for 7 days can be increased by more than 50%,and the damage strain can be reduced by 70%. A large number of crystals form on the surface of clay reinforced by microorganisms,which realizes the cementation between soil particles,fills the pores between the particles, increases the cohesion and internal friction Angle,and thus improves the strength of soil.