钙质砂土微生物加固方法与固化机理研究

Calcareous soil is widely distributed in South China Sea. With the requirement of the exploitation and national defense, much more large projects will be built in South China Sea. Calcareous soil has special engineering properties different from the general sand due to its unique characteristics of particularity, heterogeneity and regional quality. The unique engineering properties often result in troubles and difficulties in the geotechnical foundation construction. Thus, there is an urgent need to develop a new kind of method to reinforce calcareous soil foundation. The latest research progresses of microbial induced carbonate precipitation (MICP) have brought opportunities for environment-friendly modified geotechnical materials. However, the reinforcement mechanism of microbe cemented calcareous soil is still unknown. The project take calcareous soil in the South China Sea as the study, through conducting the effect of changing treatment factors, such as bacterial activity, chemical concentrations, and injection process, the optimal use and efficient control technology of microbial reinforcement calcareous soil is presented. The reinforcement mechanism of microbial induced carbonate precipitation cemented calcareous soil will be obtained by macro and micro testing. The static and dynamic behaviors of cementation treatments are studied through penetration test, unconfined compressive, static triaxial and dynamic triaxial test. The results can assess the bio-cementation in strength, deformation and permeability, get engineering parameters and guide design and construction of practical projects. The achievements can provide scientific basis for the applications of microbial modification technology in the field of foundation reinforcement in calcareous soil area.

我国南海地区分布大量的钙质砂土，随着南海诸岛开发和国防需要，岛礁和海上工程数量日趋增多。由于钙质砂的特殊性、不均匀性及区域性等特点，其工程力学特性不同于传统的砂层，引发越来越多的工程建设问题，迫切需要研发新方法对钙质砂地基进行加固。微生物诱导碳酸钙沉淀技术（MICP）为形成绿色环保型的改性土工材料带来了机遇。目前国内外针对钙质砂微生物加固机理与方法的研究尚不成熟。本课题以南海珊瑚岛礁的钙质砂为研究对象，通过控制菌液浓度、营养液浓度、灌注方法等影响因素，提出有效、可控的微生物加固钙质砂的工艺与方法；从宏观与微观角度探索微生物诱导碳酸钙沉淀技术胶结钙质砂的加固机理；通过渗透试验、无侧限抗压试验、三轴压缩试验、动三轴试验等手段研究其静、动力学特性，从强度、变形、渗透性等方面来评价加固后的效果，获得相应参数，以便指导实际工程。研究成果可为我国南海珊瑚岛礁工程建设的地基加固提供科学依据。

我国南海地区分布大量的钙质砂土，随着南海诸岛开发和国防需要，岛礁和海上工程数量日趋增多。由于钙质砂的特殊性、不均匀性及区域性等特点，其工程力学特性不同于传统的砂层，引发越来越多的工程建设问题，迫切需要研发新方法对钙质砂地基进行加固。微生物诱导碳酸钙沉淀技术（MICP）为形成绿色环保型的改性土工材料带来了机遇。目前国内外针对钙质砂微生物加固机理与方法的研究尚不成熟。本课题以南海珊瑚岛礁的钙质砂为研究对象，通过控制菌液浓度、营养液浓度、灌注方法等影响因素，提出有效、可控的微生物加固钙质砂的工艺与方法；从宏观与微观角度探索微生物诱导碳酸钙沉淀技术胶结钙质砂的加固机理；通过渗透试验、无侧限抗压试验、三轴压缩试验、动三轴试验等手段研究其静、动力学特性，从强度、变形、渗透性等方面来评价加固后的效果，获得相应参数，以便指导实际工程。研究成果可为我国南海珊瑚岛礁工程建设的地基加固提供科学依据。