纤维和煤矸石粉对膨胀土胀缩特性改性研究

Study on the Expansion and Shrinkage Characteristics of Expansive Soil Modified by Coal Gangue and Fiber Powder

为改善膨胀土的胀缩特性,利用聚丙烯纤维和煤矸石对内蒙古兴和县高庙子乡膨胀土进行改性,设计4种不同改性方案的复合土样,分别为纯膨胀土、纤维改性膨胀土、煤矸石改性膨胀土和纤维-煤矸石改性膨胀土,对4种复合土样进行膨胀率、收缩率和回弹模量试验。结果表明,纤维-煤矸石改性膨胀土的自由膨胀率和无荷膨胀率均最小,较纯膨胀土分别降低41%和54%;4种土样线缩率受含水率变化影响较大,含水率较小时,煤矸石对膨胀土线缩率的抑制作用较纤维小;随着含水率增大,煤矸石对膨胀土线缩率的抑制作用开始增大;纤维对膨胀土的体缩率抑制作用较煤矸石小,4种土样中,纤维-煤矸石改性膨胀土的体缩率最小,较纯膨胀土降低32%;各土样回弹模量随含水率增大而减小,在较大含水率时,纤维-煤矸石可减小水分子对膨胀土内部结构的破坏,从而使土体抗变形能力提高。

In order to improve the shrinkage characteristics of expansive soil,polypropylene fiber and coal gangue were used to modify the expansive soil in Gaomiaozi Township,Xinghe County,Inner Mongolia,We design pure expansive soil,fiber improved expansive soil,coal gangue improved expansive soil and fiber-coal gangue improved expansive soil composite soil samples of four different improvement schemes,the expansion rate,shrinkage rate and resilience modulus of four kinds of composite soil samples were tested.The results show that the free expansion rate and noload expansion rate of expansive soil improved by fiber-coal gangue are the smallest,which are decreased by 41%and 54%than that of pure expansive soil respectively.The linear shrinkage of four kinds of soil samples is affected by the change of water content.When the water content is small,the inhibition effect of coal gangue on linear shrinkage of expansive soil is smaller than that of fiber.With the increase of water content,the inhibition of coal gangue on the linear shrinkage of expansive soil begins to increase.Compared with coal gangue,the volume shrinkage of expansive soil modified by fiber-coal gangue is the smallest,and it is decreased by 32%than that of pure expansive soil.The modulus of resilience decreases with the increase of water content.At higher water content,the fiber-coal gangue can reduce the damage of water molecules to the internal structure of expansive soil,so that the anti-deformation ability of soil is improved.