微生物矿化碳酸钙改良土体的进展、展望与工程应用技术设计

Review,outlook and application technology design on soil improvement by microbial induced calcium carbonate precipitation

利用微生物矿化碳酸钙(Microbial Induced Calcium carbonate Precipitation,简称MICP)沉积出具有胶结功能的碳酸钙,填充土内孔隙、胶结土颗粒,能够提高土体强度、降低渗透性,具有很好的土体改良作用,在微生物注浆、加固土坝、防风固砂、库底防渗、坝体防渗、污染土壤(地下水)修复等方面具有工程应用前景。对MICP土体改良研究进行了总结、分析和展望:利用MICP技术能够将砂土的无侧限抗压强度提高到20MPa以上,渗透系数降低到处理前的1%,剪切波速提高4倍,能够胜任岩土工程任务;认为下一步应重点对处理效果的均匀性、适用的地基土范围、处理土的全面性能开展系统研究,如耐久性、动力性能和防腐性能等。MICP技术已经在砂砾体稳定、地下室堵漏中得到了少量应用,工程应用施工技术是MICP应用的瓶颈。对MICP在岩土工程领域应用的施工技术进行了设计,包括地基加固、液化地基改良、污染土壤(地下水)修复、坝体防渗堵漏和加固砂桩,以推动MICP技术的实际工程应用为盼。

Microbial induced calcium carbonate precipitation （MICP） can produce CaCO3 cementation, which may result in the improvement of strength and the reduction of permeability by filling soil pores and bonding soil particles. The improved performance of MICP implies its broad applications including microbial grouting, earth dam reinforcement, wind protection and sand fixation, seepage protection for dam and dam bottom, remediation for contaminated soil or groundwater. The studies on soil improvement by MICP were summarized, analyzed and outlooked. It is seen that with MICP, the unconfined compressive strength of sand can be improved to 20MPa, its permeability may be reduced to 1% of that of untreated sand, and its shear wave velocity may be increased to 4 times of that of untreated sand, which makes it applicable to geotechnical engineering. It is also believed that in the next research stage, emphasis shall be put on the systematic studies on the uniformity of treatment effect, the applicable scope of ground soil, and the comprehensive performance （ such as durability, dynamic performance, corrosion resistance, etc. ） of treated soil. To a small extent, MICP has been applied to the stabilization of gravel soil and leakage prevention of basement, h is found that construction technologies are the bottleneck of MICP in practical egnineering application. Construction technologies of MICP in geotechnical engineering are designed, including ground reinforcement, improvement of liquefied ground, remediation of contaminated soil （ or groundwater） , leakage prevention of dam and sand pile reinforcement, so that MICP technologies can be broadly applied to engineering practice.