微生物分解硅酸盐矿物增黏对砂土强度的影响  

Effects of clay content increasement by microbial decomposition of silicate minerals on the strength characteristics of sand

作　　者：王杰[1] 邵光辉[1] 丁嘉 WANG Jie;SHAO Guanghui;DING Jia(College of Civil Engineering,Nanjing Forestry University,Nanjing 210037,China)

机构地区：[1]南京林业大学土木工程学院,南京210037

出　　处：《林业工程学报》2024年第4期154-161,共8页Journal of Forestry Engineering

基　　金：国家自然科学基金(51578293)。

摘　　要：砂土因其无黏聚力而易导致地震液化和渗流侵蚀等工程病害问题,微生物矿化与分解技术的发展为提高砂土黏聚力提供了新的可能。利用胶质芽孢杆菌能够分解硅酸盐矿物的特性,采取人工营养液激励加速含钾长石、黑云母等硅酸盐矿物砂土的生物风化,分析经微生物处理前后砂土的强度参数、黏粒含量、矿物组分和粒间微结构的变化规律。结果表明:胶质芽孢杆菌处理后的砂土中黏粒含量增加了1.6%;黏聚力与处理时长呈线性正相关,120 d内有效黏聚力增加了23 kPa,有效内摩擦角则有轻微的减小;砂土中的钾长石、黑云母等硅酸盐矿物均产生了不同程度的分解破坏,X射线衍射谱图显示,微生物处理120 d后砂土中出现了新的高岭石衍射峰,表明胶质芽孢杆菌分解了黑云母和钾长石等硅酸盐矿物,产生次生黏土矿物高岭石,使砂土中黏粒含量增加。微生物分解硅酸盐矿物产生黏土矿物和胞外聚合物是砂土黏聚力提升的主要原因。营养物激励下矿物分解菌对硅酸盐矿物的风化作用对于改善砂土抗液化和抗渗流性能具有潜在的价值。Sand foundation is prone to engineering distresses such as seismic liquefaction and seepage erosion for its cohesionless characteristics.The clay content in soil is an important factor to affect the cohesion,which contributes to prevent seismic liquefaction and seepage erosion of the soil.The development of microbial mineralization and decomposition technology provides new possibilities to improve the cohesion of sand.The Bacillus mucilaginosus that can decompose silicate minerals was adopted to accelerate the biological weathering of sand containing silicate minerals such as potassium feldspar and black mica under artificial nutrient solution stimulating condition.The changing rules of the strength properties,clay content,mineral component,and intergranular microstructure of the sand before and after the microbial treatment were investigated.The results showed that the clay content in the sand treated by B.mucilaginosus was increased by 1.6%when compared with that before treatment.There was a positive linear correlation between cohesion and processing time,as well as the effective cohesion was increased by 23 kPa within 120 d.How-ever,the effective internal friction angle was decreased slightly after the microbial treatment.The stress-strain curves of sand samples treated by B.mucilaginosus showed strain softening characteristics under different confining pressures,and the peak strain of partial stress was gradually decreased with the increase in treatment age,and the strain softening characteristics of soil were obviously enhanced.Silicate minerals such as potassium feldspar and biotite in sandy soil are decomposed and destroyed in different degrees.The surface of the massive potassium feldspar in the sand was broken,and the thin layer fell off,and the overall structure did not change significantly.The surface of the sheet biotite was uneven and cracked,as well as the decomposition effect of B.mucilaginosus was remarkable.The X-ray diffraction spectra of sample treated for 120 d showed new diffraction peaks of

关 键 词：胶质芽孢杆菌 抗液化 硅酸盐矿物 黏聚力 黏粒含量 

分 类 号：TU44[建筑科学—岩土工程]