微生物改性水泥土的制备与力学特性研究

Preparation and Mechanical Properties of Cement Soil Modified by Sporosarcina pasteurii

花岗岩残积土在我国华南地区广泛分布,由于其具有明显的遇水崩解特性,往往带来山体滑坡等地质灾害。基于微生物诱导碳酸钙沉淀技术(MICP)采用巴氏芽孢杆菌对水泥加固花岗岩残积土的工程性质、工程技术进行改良研究,探究以水泥掺入量、钙离子浓度和钙源等因素为变量时,MICP技术对水泥土强度、应力应变关系等力学性能的影响。通过无侧限抗压强度(UCS)试验,分析了经MICP加固后水泥土的力学强度,得到以下结论:①MICP技术可以明显增强花岗岩残积土为基材的水泥土的强度、刚度和韧性等工程性质;②与对照组相比,试验组强度最大增长率为87.5%,最经济的水泥掺入量为15%;③氯化钙和乙酸钙为钙源都可以改善试样的韧性,而乙酸钙的效果更好,与对照组相比,试验组应变最大增长率为69.67%,此时所对应的钙离子浓度为0.5 mol/L。

Widely distributed in south China,granite residual soil often brings about landslide and other geological disasters as it disintegrates obviously when confronted with water.In this research,the engineering properties and engineering techniques of cemented granite residual soil were improved by adding bacillus pasteurii using microbial induced calcite precipitation(MICP)technology.The influence of MICP technology on the mechanical properties of cemented-soil such as strength and stress-strain relationship was examined when factors such as cement mixing ratio,calcium ion concentration and calcium source were taken as variables.Unconfined compressive strength(UCS)test was conducted to analyze the mechanical strength of cemented-soil strengthened by MICP,and conclusions were obtained as follows:1)MICP technology significantly enhanced the engineering properties inclusive of strength,stiffness and toughness of cemented granite residual soil;2)compared with the control group,the maximum growth rate of strength in the test group amounted to 87.5%,and the most economical cement mixing ratio was 15%;3)calcium chloride and calcium acetate could both improve the toughness of test specimens,and the effect of calcium acetate was superior;compared with the control group,the maximum growth rate of the toughness of the test group reached 69.67%when the calcium ion concentration was 0.5 mol/L.