MICP加固粉土的渗透特性及微观机理  

Permeability characteristics and micro-mechanism of MICP-reinforced silt

作　　者：彭丽云 杜辛涛[1] 齐吉琳 王剑烨 朱同宇[3] PENG Liyun;DU Xintao;QI Jilin;WANG Jianye;ZHU Tongyu(School of Civil and Transportation Engineering,Beijing University of Civil Engineering and Architecture,Beijing 100044,China;Beijing International Science and Technology Cooperation Base of Urban Transportation Infrastructure Construction,Beijing University of Civil Engineering and Architecture,Beijing 100044,China;Shandong Rail Transit Survey and Design Institute Co.,LTD.,Jinan 250101,China)

机构地区：[1]北京建筑大学土木与交通工程学院,北京100044 [2]北京建筑大学城市交通基础设施建设北京市国际科技合作基地,北京100044 [3]山东轨道交通勘察设计院有限公司,济南250101

出　　处：《北京交通大学学报》2023年第6期154-162,共9页JOURNAL OF BEIJING JIAOTONG UNIVERSITY

基　　金：国家自然科学基金(42172299,41972279,42202309)。

摘　　要：针对黄河冲积平原地区的粉土颗粒均匀、黏聚力低、水稳性差,雨季时易出现水害,然而现有加固方法环保性不足的问题,利用绿色环保的微生物诱导碳酸钙沉淀(Microbially Induced Calcite Precipitation,MICP)技术进行加固.首先,选用巴氏芽孢杆菌作为微生物,通过多轮注浆制得MICP加固土样.然后,采用三轴渗透试验研究其渗透特性.最后,结合其内部碳酸钙含量测定、电镜扫描结果揭示微观机理.研究结果表明:MICP加固可使粉土渗透系数降低96%;渗透系数和其内部平均碳酸钙产量之间呈线性关系,且渗透系数随胶结液浓度和加固轮数的增加而降低,但趋势逐渐变缓.MICP反应在粉土中产生的碳酸钙晶体为菱形聚合物,且主要分布在粉土颗粒表面、土颗粒间孔隙及孔喉处,起到覆膜、粘连和封堵作用,进而降低渗透系数.相关研究成果可为MICP技术在改良加固粉土中的应用提供理论支持和技术参考.The silt in the Yellow River alluvial plain is characterized by uniform particles,low cohe-sion,and poor water stability,leading to susceptibility to water damage during the rainy season.Tradi-tional reinforcement methods often lack environmental sustainability.This study employs the environ-mentally friendly Microbially Induced Calcite Precipitation(MICP)technology for reinforcement.Firstly,Bacillus pasteuri is chosen as the microorganism,and the MICP-reinforced soil samples are prepared by multi-round grouting.Then,the triaxial permeability test is conducted to study the perme-ability characteristics.Finally,the microscopic mechanism is revealed through the determination of cal-cium carbonate content and electron microscope scanning.The results show that the permeability coef-ficient of silt can be reduced by 96%by the MICP reinforcement.There is a linear relationship be-tween the permeability coefficient and the average output of calcium carbonate,and the permeability coefficient decreases with the increase of cement concentration and the number of reinforcement wheels,although the trend gradually slows down.MICP-induced calcium carbonate crystals in silt form rhombohedral polymers,primarily distributed on the surface of silt particles,pores,and throats between soil particles.These crystals function to film,adhere,and plug,thus reducing the permeabil-ity coefficient.These research findings provide theoretical support and technical reference for the appli-cation of MICP technology in improving and strengthening silt.

关 键 词：路基工程 黄河冲积粉土 微生物诱导碳酸钙沉淀 渗透特性 影响因素 微观机理 

分 类 号：TU444[建筑科学—岩土工程]