中文摘要：

【目的】确定微生物诱导碳酸钙沉积（MICP）技术注浆固化吹填粉土的强度效果,明确其微观控制因素与固土作用机理,为微生物固土技术应用于处理吹填粉土提供理论参考。【方法】通过不同注浆轮次微生物注浆固化吹填粉土,采用无侧限抗压试验、X射线衍射分析、扫描电镜分析、压汞分析以及化学分析等方法,比较微生物注浆固化处理吹填粉土的强度、矿物成分、胶结CaCO3含量、土体微观形貌和土体孔径分布等差异。【结果】对吹填粉土先后恒压注入A600=1.2的巴氏芽孢杆菌和0.1 mol/L的CaCl2与尿素胶结溶液1～6轮后,其无侧限抗压强度较未处理土分别提高26.8%、33.0%、36.4%、39.6%、59.8%、61.8%,强度随注浆轮次的增加而增加;微生物固化吹填粉土中的主要胶结物为方解石型CaCO3,其在土体内部起到胶结土颗粒与填充孔隙两方面作用,微生物注浆固化粉土强度随CaCO3含量增加而增加并存在敏感阈值,当固化粉土中的CaCO3含量超过阈值时,固化效果会显著提升,不同粉土的阈值存在差异;微生物注浆加固改变了吹填粉土的孔隙分布,直径10～300μm的孔隙显著减少,对10μm以下细小孔隙影响不大。【结论】采用微生物注浆方式固化吹填粉土是有效的。微生物注浆固化粉土的强度形成受其微观胶结结构与CaCO3含量影响,吹填粉土的孔隙尺寸能够与巴氏芽孢杆菌的菌体尺寸相容,微生物注浆会显著减少吹填粉土中10μm以上的孔隙。

英文摘要：

【Objective】Determining the behavior of microbial cementation silt treated by bio-grouting,based on the technology of microbial induced carbonate precipitation（MICP）,could provide a basis for developing the MICP technology and applying it for dredger fill silt.【Method】Experiments were conducted for cement dredger fill silt specimens by microbial grouting.Unconfined compressive tests,X-ray diffraction analyses（XRD）,scanning electron microscope（SEM） observations,mercury intrusion porosimetry（MIP） and some chemical analyses were performed to investigate the difference in strength,mineral component,cementing CaCO3 content,soil microstructure and pore size distribution of untreated and treated dredger fill silts.【Result】After injecting 1 to 6 rounds of Sporosarcina pasteurii（A600= 1.2）and a cement solution containing a mixture of CaCl2 and urea（0.1 mol/L） under constant pressure,the unconfined compressive strength of the treated silt specimens increased by 26.8%,33.0%,36.4%,39.6%,59.8% and 61.8% after the rounds 1 to 6,respectively,compared to the untreated silt specimen.The strength of the treated silt specimens increased with the number of rounds of injection.The cementing CaCO3 from the microbial grouting was mostly in the calcite phase,which filled the soil pores and cemented the soil particles.The CaCO3 content had a dominant effect on the strength of the treated silt.The more the CaCO3 precipitated from the microbial process in the silt,the higher was the strength of the silt.Furthermore,there was a sensitive threshold for CaCO3 content with respect to strength variation.The cementing efficiency increased significantly when the CaCO3 content was higher than the threshold,which varied with the genetic type or sedimentary environment of the silt.Compared to the untreated silt,the treated silt had significantly different pore diameter distribution characteristics.After the bio-grouting treatment,the pores in the range 10-300 μm in thesilt reduced sharply,and the pores smaller tha