脲酶抑制剂对微生物改良红黏土收缩特性的影响  

Effect of Urease Inhibitors on Shrinkage Properties of Microbial Modified Red Clay

作　　者：欧阳以 彭成 李超 OUYANG Yi;PENG Cheng;LI Chao(School of Civil Engineering,University of South China,Hengyang,Hunan 421001,China)

机构地区：[1]南华大学土木工程学院,湖南衡阳421001

出　　处：《南华大学学报(自然科学版)》2024年第6期46-53,77,共9页Journal of University of South China:Science and Technology

基　　金：水利部土石坝破坏机理与防控技术重点实验室开放基金项目(YK319008)。

摘　　要：本试验分析脲酶抑制剂—正丁基硫代磷酸三胺(N-(N-butyl)thiophosphoric triamid,NBPT)不同掺量对MICP(microbial induced carbonate precipitation,MICP)灌浆改良红黏土收缩特性影响,通过对CaCO_(3)生成量测定、XRD(X-ray diffraction,XRD)衍射和SEM(scanning electron microscope,SEM)电镜扫描试验,对试样进行微观结构特征观察,综合分析NBPT对MICP改良红黏土收缩特性的作用机制,评价了引入NBPT后微生物改良红黏土收缩性能影响的效果,结果表明:MICP改良红黏土试样的收缩变形量、初始含水率及收缩系均随着NBPT的掺量增大逐渐减小。在残余收缩变形阶段(δ_(s2)),随着NBPT掺量增大,试样达到极限线性收缩率的含水率逐渐增大,使其更早地进入稳定收缩变形阶段(δ_(s3))。可以有效延缓MICP改良后红黏土整体收缩速率,随着NBPT掺量增大土样整体收缩变形量减小,整体收缩过程结束更早。试样CaCO_(3)总生成量随NBPT掺量增大呈先增大后减小的变化趋势;上下部CaCO_(3)生成量差值随着NBPT掺量增大而逐渐减小,最后趋于稳定。脲酶抑制剂NBPT可以影响生成物晶体形貌和分布情况,以及干预球霰石向方解石的形态转化;NBPT的掺量越大,MICP技术在填充红黏土中细小孔隙的能力越强,CaCO_(3)分布更均匀,从而改善MICP对红黏土收缩特性的改良效果。In this experiment,the effects of urease inhibitor N-(N-butyl)thiophosphoric triamid(NBPT)with different content on the shrinkage properties of red clay improved by MICP(microbial induced carbonate precipitation)grouting were analyzed.The microstructure characteristics of the samples were observed by CaCO_(3) content determination,XRD diffraction and SEM electron microscope scanning test.The mechanism of NBPT on the shrinkage properties of MICP improved red clay was comprehensively analyzed.The effect of microorganism on the shrinkage of red clay improved by NBPT was evaluated.The results showed that the shrinkage deformation,initial moisture content and shrinkage system of red clay improved by MICP decreased with the increase of NBPT content.In the residual shrinkage deformation stage(δ_(s2)),with the increase of NBPT content,the moisture content of the sample reaching the limit linear shrinkage gradually increases,which makes it enter the stable shrinkage deformation stage earlier(δ_(s3)).It can effectively delay the o verall shrinkage rate of red clay improved by MICP.With the increase of NBPT content,the overall shrinkage deformation decreases,and the overall shrinkage process ends earlier.The total amount of CaCO_(3) in the sample increased at first and then decreased with the increase of NBPT content.The difference of CaCO_(3) content between the upper and lower parts decreased gradually with the increase of NBPT content,and finally tended to be stable.Urease inhibitor NBPT can affect the crystal morphology and distribution of the product,and interfere with the morphological transformation of graupel to calcite;the greater the content of NBPT,the stronger the ability of MICP technology to fill small pores in red clay,and the more uniform distribution of CaCO_(3) thus improving the effect of MICP on the shrinkage properties of red clay.

关 键 词：微生物诱导碳酸钙沉积 脲酶抑制剂 红黏土 收缩性 

分 类 号：TU446[建筑科学—岩土工程]