黄土具有多孔亚稳结构和水敏性,遇水时易发生崩解.黄土的崩解性是促进黄土高原地区水土流失、崩塌、滑坡等地质灾害发生的主要因素之一.作为一种造价低、应用方便的材料,水泥改良黄土(cement improved loess,CIL)在黄土地基、边坡工程中应用广泛,但其抗崩解性研究较少.为此,该文通过原状及不同掺量下的CIL室内崩解试验和扫描电子显微镜(scanning electron microscope,SEM)试验,分析改良前后黄土的崩解行为,探究水泥对黄土崩解性的改良效果及作用机制.结果表明,掺入水泥可大幅提升黄土的抗崩解能力,低掺量下CIL仍具有完整的崩解过程,但水泥能填充粒间孔隙,阻碍水分运移,同时水泥水化物及其与黄土颗粒的作用能增强粒间胶结,从而延缓了黄土崩解进程.随着水泥掺量的增加,抗崩解效果愈明显,累积崩解百分量几乎为0.土样不发生崩解的最小水泥掺量为3％.研究结果对黄土的抗侵蚀性研究和防灾工程设计具有重要意义.
Experimental study on disintegration of loess improved by cement
Loess has porous metastable structure and water sensitivity,and is prone to collapse when it en-counters water.The disintegration of loess is one of the main factors that promote soil erosion,collapse,land-slide and other geological disasters in the Loess Plateau.As a low cost and convenient material,cement im-proved loess(CIL)is widely used in loess foundation and slope engineering,but there are few researches on its anti-disintegration.The disintegration behavior of loess before and after the improvement was analyzed through the laboratory disintegration test and scanning electron microsope(SEM)test under the condition of CIL and different content、and the improvement effect and mechanism of cement on loess disintegration were explored.The results show that cement can greatly improve the anti-disintegration ability of loess.At low con-tent,CIL still has a complete disintegration process,but cement can fill the intergranular pores and hinder wa-ter transport.Meanwhile,cement hydration and its interaction with loess particles can enhance intergranular cementation,thus delaying the disintegration process of loess.With the increase of cement content,the anti-disintegration effect is more obvious,and the cumulative disintegration component is almost 0.The minimum cement content of soil sample without disintegration is 3％.The results are of great significance to the study of erosion resistance of loess and the design of disaster prevention engineering.
loesscementthe property of disintegrationimproved soilSEM
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