MICP技术改良黄泛区土体力学性能研究  

Study on mechanical properties of soil in Yellow River flooding area improved by MICP technology

作　　者：张宝玺 岳建伟[1] 张慧[1] 赵丽敏[1] 孔庆梅[1] 顾丽华[1] 卢会芳[1] Zhang Baoxi;Yue Jianwei;Zhang Hui;Zhao Limin;Kong Qingmei;Gu Lihua;Lu Huifang(School of Civil Engineering and Architecture,Henan University,Kaifeng 475004,China)

机构地区：[1]河南大学土木建筑学院,河南开封475004

出　　处：《建筑科学》2020年第7期79-86,共8页Building Science

基　　金：黄泛区组合桩承载机理和沉降特性研究;162300410012。

摘　　要：黄泛区土存在结构松散、强度低、水稳定性差等不利特性,给黄河流域的工程建设带来潜在隐患。本文以MICP为核心技术,研究提高黄泛区土体基本力学特性,以期为黄泛区地基加固、边坡防护以及土遗址保护等工程提供技术支撑。首先由人工接种培育巴氏芽孢杆菌,通过紫外分光光度计、电导率仪分别测定细菌的OD值及活性;其次,以开封土为研究对象,采用拌和的方式将菌液与胶结液直接加入到土中,利用MICP技术改良黄泛区粉质粘土。研究表明:培养48h后细菌的OD值在1.5左右,电导率约为0.01(ms/cm·min),短时间内该细菌活性并不高,但给予细菌足够的反应时间,细菌仍能诱导大量的碳酸钙沉淀,对土体起到加固作用;控制胶结液浓度为0.5M,胶菌质量比为2∶1时产碳酸钙量最多且Ca2+转化率在80%以上;基于最优配比下黄泛区土的直接快剪试验和不固结不排水剪试验结果,土的粘聚力提高了约30%,内摩擦角变化不大,不同垂直压力下剪应力、不同围压下有侧限抗压强度及地基承载力特征值均有所提高。The soil in the Yellow River flood area has some unfavorable characteristics such as loose structure,low strength and poor water stability,which brings potential hazards to the engineering construction of the Yellow River Basin.In this paper,MICP is the core technology to study and improve the basic mechanical properties of soil in the Yellow River flood area,in order to provide technical support for the foundation reinforcement,slope protection and soil heritage protection projects in the yellow River flood area.Firstly,Bacillus Pasteurella is cultivated by artificial inoculation,and the OD value and activity of bacteria are measured by ultraviolet spectrophotometer and conductivity meter respectively.Secondly,Kaifeng soil is taken as the research object,the bacterial liquid and cementation liquid are directly added into the soil by mixing,and the silty clay in the Yellow pan area is improved by using MICP technology.The results show that:the OD value of bacteria is about 1.5 and the conductivity is about 0.01(ms/cm·min)after 48 h culture,the activity of bacteria was not high in a short period of time,but gives enough reaction time,the bacteria could still induce a large amount of calcium carbonate precipitation and play a reinforcing role in soil;when the concentration of cementing solution is 0.5 M and the ratio of colloid bacteria is 2∶1,the yield of calcium carbonate is the largest and the conversion rate of Ca2+is more than 80%;based on the results of direct fast shear test and unconsolidated undrained shear test,the cohesion of the soil is increased by about 30%,the internal friction angle has little change,and the characteristic values of shear stress,confined compressive strengthunder different confining pressures and bearing capacity of foundation under different vertical pressures are all increased.

关 键 词：黄泛区土 粘聚力 MICP 胶结液 胶菌质量比 

分 类 号：TU44[建筑科学—岩土工程]