微生物矿化对塔基弃土的固结作用及抗降雨侵蚀效果

输变电线路工程建设过程会产生大量弃土,因土体松散受降雨作用极易饱和形成渗流,从而诱发滑坡和水土流失。本研究在输变电工程水土保持仿真模拟试验平台,通过喷洒方式向塔基弃土添加微生物矿化菌液和胶结液,分析测定土壤试样的干密度、孔隙度、渗透性、液限、塑限、压缩性、抗剪切强度等土力学指标,用射线衍射(X-ray diffraction,XRD)和扫描电镜(scanning electron microscopy,SEM)表征矿化试样的晶体类型和微观形貌,最终将技术工艺在输电线路工程现场进行示范应用。结果表明,喷洒微生物矿化菌液和胶结液,可在塔基弃土孔隙中形成方解石型碳酸钙晶体,使塔基弃土更加密实,增大干密度,降低孔隙度和渗透系数,且液限增高5%,塑限降低5%,赋予土壤更好的可塑性,内摩擦角从29.97°提高到了32.62°,提高土壤的抗剪强度,对塔基弃土浅层具有很好的固结作用,可显著降低受不同等级强度降雨侵蚀的产沙量,从而减少因降雨侵蚀造成的水土流失,现场示范也进一步证明了抗降雨侵蚀效果,微生物矿化技术可非常明显地减少流失斑。因此,微生物矿化技术可作为输变电线路工程建设的一项绿色、环保、简便、高...

The Idation Effect and Anti-rainfall Erosion of Microbially Induced Carbonate Precipitation on Abandoned Soil of Transmission Tower

The construction of power transmission and transformation line would produce a large amount of abandoned soil. Due to the loose soil and rainfall, it is easy to be fully saturated and form seepage, thus inducing landslide and causing soil erosion. Based on the simulation test platform of soil and water conservation in the power transmission and transformation project, the study aimed to add microbially induced carbonate precipitation bacteria liquid and cement liquid to the abandoned soil by spraying, and then collect data of soil mechanical indexes including density, porosity, permeability, liquid limit, plastic limit, compressibility and shear strength for further evaluation. Besides, the crystal type and microscopic morphology of mineralized samples were characterized by XRD and SEM. The optimal operation conditions were applied in the sites of transmission lines. The results show that calcite calcium carbonate crystals can be formed in the pores of abandoned soil with the adhesive fluid addition of microbial mineralization bacteria, achieving more dense tower base with increased dry density and lower porosity and permeability coefficient. Better soil plasticity was achieved with the liquid limit increased by 5% and the plastic limit reduced by 5%. The shear strength of the soil was enhanced with the internal friction angle rising from 29.97 to 32.62, offering an effective consolidation on the shallow layer of the abandoned soil to significantly reduce the sand yield eroded by different rainfall intensities. Field demonstration further proved the anti-rainfall erosion effect where microbial mineralization technology played a significant role. Therefore, microbial mineralization technology is potentially a environmental friendly and efficient measure for soil and water conservation in hte construction of power transmission and transformation line.