微生物矿化粉土的胶结液配比优化试验研究

Laboratory study on the optimization of cementing solution ratio for microbial treated silt

微生物诱导碳酸钙沉淀(MICP)技术是岩土材料加固的新兴手段,然而当前胶结液配比对微生物加固粉土工程特性的影响尚不明晰,致使其工程应用缺乏理论依据。通过系列宏微观室内试验,探明微生物矿化粉土的最优胶结液(氯化钙∶尿素)配比,研究最优胶结液配比下微生物矿化粉土的抗压特性、抗剪特性、渗透特性以及微观结构特征。结果表明:微生物加固可促使试样的应力—应变关系由弱软化型向强软化型发展,并使得渠基土的渗透系数降低至少一个数量级;当养护龄期为28d时,微生物加固试样黏聚力最大提升幅度达86.51%,表明微生物矿化作用可以有效提升试样的物理力学性能。同时,当胶结液配比(氯化钙∶尿素)为1∶1时,微生物加固粉土的作用效果最为显著。研究成果为微生物岩土加固技术科学研究与工程应用提供参考。

Microbial induced calcium carbonate precipitation(MICP)technique is an emerging method for geotechnical material treatment.However,the effects of the cementation ratio on the engineering properties of the microbial treated silt are not clear,resulting in a lack of theoretical basis for its engineering application.Through a series of macro and micro laboratory tests,the optimal cementation ratio(calcium chloride∶urea)of the microbial treated soil is explored,and the compressive characteristics,shear resistance,permeability characteristics and microstructure characteristics of the microbial treated soil under the optimal cementation ratio are studied.The results show that microbial treatment can promote the stress-strain relationship of the specimen to develop from weak softening type to strong softening type,and reduce the permeability coefficient of the soils by at least one order of magnitude;as the curing age is 28 days,the maximum increase in cohesion of the microbial treated soil is 86.51%,indicating that microbial treatment can effectively improve the physical and mechanical properties of the specimens.Meanwhile,when the ratio of cementation solution(calcium chloride∶urea)is 1∶1,the effect of microbial treatment on loess is most significant.The study results provide the reference for the scientific research and engineering application of microbial treatment technique.