MICP加固砂土方法对比研究

Comparative study on MICP-treatment schemes for sands

微生物诱导碳酸钙沉淀(MICP)技术是新兴的岩土工程绿色加固技术,在散粒土加固方面具有良好的应用前景。MICP加固砂土的均匀性和力学表现是目前存在的重要问题,为优化MICP加固方法,改善加固后砂土的综合表现,开展MICP加固砂土方法对比试验研究。详细介绍了传统两相法、pH法及温控法MICP加固方案,利用传统两相法、pH法及温控法开展砂柱试样的MICP加固试验,从加固试样的碳酸钙分布均匀性、反应液中钙离子利用率及加固试样的无侧限抗压强度等3个方面对比分析3种MICP加固方法的综合表现。结果表明:在试验条件下,传统两相法在3方面均表现最差;pH法和温控法整体表现较好,其中温控法反应液利用率较高,在高加固程度时强度略高,综合表现最优。

Microbially induced calcium carbonate precipitation(MICP)is a new green ground improvement technique in geotechnical engineering and has a promising prospect in reinforcing granular soils.The uniformity and the mechanical performance of MICP-treated sands are important issues in the MICP method.To optimize the MICP-treatment scheme and improve the overall performance of MICP-treated sands,a comparative experimental study on different MICP-treatment schemes for sands was carried out.Firstly,the MICPtreatment schemes,including the conventional two-phase method,the pH method and the temperaturecontrolled method,were introduced in detail.Then,a series of MICP-treatment experiments on sand columns were conducted,following the three different schemes,respectively.Finally,the three different schemes were compared in terms of the distribution of CaCO3 in the post-treatment specimens,the utilization rate of reaction solutions and the unconfined compressive strength of the post-treatment specimens.Under the testing conditions in this paper,the conventional two-phase method has the worst performance in the three aspects;the pH method and the temperature-controlled method generally perform well;in comparison with the pH method,the temperature-controlled method has a higher utilization rate of reaction solutions and a higher strength under hightreatment conditions;the temperature-controlled method has the best overall performance.