微生物诱导碳酸钙沉淀技术改良黄土湿陷性研究

Microbial Induced Calcium Carbonate Precipitation Technique for Improving Collapsibility of Loess

为有效降低黄土地区遇水产生的湿陷性,以兰州黄土为研究对象,利用微生物诱导碳酸钙沉淀(MICP)技术对黄土湿陷性进行研究。首先对MICP处理前后黄土的无侧限抗压强度及湿陷系数进行评价,然后利用CT扫描技术分析MICP改良后的黄土微观特征,进一步探究MICP改良机理。试验结果表明:经MICP处理后的黄土试样无侧限抗压强度显著提高,最高可达150 kPa,黄土湿陷性有效降低;随着胶结液浓度不断增加,碳酸钙生成量持续增加,但在胶结液浓度大于1.25 mol/L时,碳酸钙生成量呈下降趋势;改良后黄土试样的孔隙率、孔隙等效直径等指标均降低。

In order to effectively reduce the collapsibility of loess areas in contact with water,a study was conducted on the collapsibility of loess using microbial induced calcium carbonate precipitation(MICP) in Lanzhou loess.The unconfined compressive strength and coefficient of collapsibility of the loess before and after MICP treatment were evaluated.The microscopic characteristics of loess modified by MICP were analysed by CT scanning technology,and the improvement mechanism of MICP was further explored.The test results show that the unconfined compressive strength of the loess specimens modified by MICP increases significantly,up to 150 kPa,and the collapsibility of the loess is effectively reduced;the amount of calcium carbonate production continues to increase with the increasing concentration of the cementing fluid,but decreases when the concentration of the cementing fluid is greater than 1.25 mol/L;the porosity and pore equivalent diameter of the modified loess specimens are decreased.The porosity and pore equivalent diameter of the modified loess specimens are all reduced.