微生物灌浆加固砂土效果的试验研究  

Experimental study on reinforcement effect of microbial grouting on sandy soil

作　　者：余清鹏 李娜[1,2] 符平 王丽娟[1,2] 李凯 YU Qingpeng;LI Na;FU Ping;WANG Lijuan;LI Kai(China Institute of Water Resources and Hydropower Research,Beijing 100048,China;Beijing IWHR Corporation ,Beijing 100048,China)

机构地区：[1]中国水利水电科学研究院,北京100048 [2]北京中水科工程总公司,北京100048

出　　处：《中国水利水电科学研究院学报》2019年第3期204-210,共7页Journal of China Institute of Water Resources and Hydropower Research

基　　金：国家重点研发计划项目(2016YFC0401609);中国水科院科研专项(EM0145B172018)

摘　　要：利用微生物灌浆对砂土地基进行防渗加固处理是一种新型的地基处理方法,材料的浓度是影响灌浆效果的重要因素。本文采用小尺度微生物灌浆试验研究了不同菌液浓度、钙源浓度及尿素浓度对砂土灌浆效果的影响,通过环境电镜扫描(E SEM)分析了砂土颗粒的结晶体的形态变化,揭示了微生物成因和生长规律,通过力学和渗透试验探讨了加固体的强度和渗透特性。研究表明,随着菌液浓度的增加,菌液的活性有明显的提高,微生物结晶体呈多级生长,砂柱的抗压强度有所提高,菌体分泌的胶质有机物也会提高砂柱的抗渗透能力,但菌液浓度过高则对改善砂土的指标有限,可根据工程防渗加固的不同要求选择合适的菌液浓度。钙离子浓度为1,尿素浓度为2时,砂柱的结晶体均匀致密,灌浆效果较好。实验得到的砂柱最大抗压强度为22.5MPa,最小渗透系数为2.12×10^-5 cm/s。研究结果对促进微生物灌浆技术的应用具有指导意义。Microbial grouting is a new method for seepage control and reinforcement of sand foundation, and the concentration of materials is an important factor affecting grouting effect. By small-scale microbial grouting test,the influences of different concentration of bacteria,calcium and urea on grouting effect of sand soil are studied. Morphological changes of sand particles’surface crystals are analyzed by environmen tal scanning electron microscopy (ESEM). The mechanism and growth law of microbe are revealed. The characteristics of strength and permeability of reinforced solid are discussed by mechanical and permeability tests. The results show that with the increase of bacteria concentration,bacterial activity is obviously im proved,microbial crystal is multistage growth,the compressive strength of sand column is improved,and the colloidal organic matter secreted by the bacteria can also improve the permeability resistance of sand column. However,if bacteria concentration is too high,the index of improving sand soil will be limited. Therefore,the appropriate bacteria concentration can be selected according to the different requirements of seepage control and reinforcement in engineering. When calcium concentration is 1 and urea concentration is 2,the crystal formation of sand column is uniform and dense,and the grouting effect is good. The maxi mum compressive strength of sand column is 22.5 MPa and the minimum permeability coefficient is 2.12×10^-5cm/s. The results have guiding significance for promoting the application of microbial grouting technology.

关 键 词：砂土地基 防渗加固 微生物灌浆 环境电镜扫描 

分 类 号：TU435[建筑科学—岩土工程]