聚丙烯纤维和水泥对粘性土强度的影响及机理研究

选取聚丙烯纤维和水泥作为加固材料,在室内试验的基础上,研究了单独的纤维和水泥对粘性土强度的影响及其的综合作用,分析了它们的作用机理。试验中,3种不同百分比(0.05%,0.15%和0.25%素土重)的纤维和两种不同百分比的(5%和8%素土重)水泥分别掺入到粘土试样中,配制了12组试样,进行了无侧限抗压试验。试验结果表明,纤维和水泥均能够提高土体的强度,纤维的加入改善了水泥土样的脆性破坏模式;纤维水泥土样的强度远远高于相同掺量下的纯纤维土和纯水泥的强度,甚至高于它们的强度之和。运用扫描电镜(SEM)从微观层次上分析了纤维和水泥加固粘性土的力学机理,发现纤维表面与土介质之间的粘结力和摩擦力对加固效果有直接影响。

EFFECTS OF POLYPROPYLENE FIBER AND CEMENT ADDITIVES ON STRENGTH BEHAVIOR OF CLAY SOIL AND THE MECHANISMS

Fiber as a good reinforcement material was mainly applied to cement and concrete,however,very limited information has been reported on the use of randomly distributed discrete fibers for soil reinforcement.In this paper,an experimental program was reported to study the individual and combined effects of randomly oriented fiber and cement additives on the geotechnical characteristics of clay soil.Three percentages of fiber contents,i.e.(0.05)%,0.15% and 0.25% by weight of raw soil and two percentages pf cement contents,i.e.,5% and 8% were randomly included in to the soil.Twelve samples were prepared and subjected to unconfined compression tests.The results of this study clearly show that both the polypropylene fiber and cement can improve the strength and stability of raw soil.Fiber inclusion can change the brittle behavior of cement soil to the ductile behavior.The increase in the strength caused by the combined action of cement and fiber is more than the sum of the increase caused by each of them individually.Polypropylene fibers are characterized in terms of their mechanical properties and microstructures.The microstructures were obtained from scanning electron microscopy(SEM) analysis.It is found that there are interfacial interactions between fibers and other substance(such as the hydrations of cement,minerals of clay soil),which can produce significant effects on the bonding strength and friction between the reinforcement and the soil matrix.