干湿循环作用下非饱和压实黄土变形和电阻率特征的室内试验

Laboratory Tests on Deformation and Resistivity Characteristics of Unsaturated Compacted Loess Under Dry-wet Cycles

摘要:

开展了干湿循环作用下非饱和压实黄土变形和电阻率特征的室内试验。首先，获取经历5次干湿循环过程的试样体积变形和电阻率特征以及干燥后表面裂隙；其次，采用恒应变速率法研究不同含水率试样的压缩性质，同时获取电阻率特征；最后，开展了核磁共振和扫描电镜测试以探究试样微观特征。结果表明，随着干湿循环次数的增加，试样膨胀应变和裂隙比增大，而电阻率减小，并均趋于稳定；3次干湿循环后试样的屈服应力明显减小，弹、塑性压缩指数增大；随着干湿循环次数的增加，土体内部小孔隙数量明显增加，中、大孔隙数量变化不明显。

Abstract:

Laboratory tests on the deformation and resistivity characteristics of unsaturated compacted loess under dry-wet cycles were carried out. First， the volume deformation and resistivity characteristics during cycling， as well as surface cracks after the desiccation of the sample undergoing five dry-wet cycles were obtained. Then， compression properties of the sample with different water contents were studied by the constant rate of strain （CRS） method， and the resistivity was also obtained. Finally， the nuclear magnetic resonance imaging and scanning electron microscopy were used to study the microscopic characteristics of the sample. The results show that with the increase of the number of dry-wet cycles， the swelling stain and crack ratio of the sample increase and the resistivity decreases， all of them tend to be stable as well. The yield stress significantly decreases and the elastic and plastic compression indexes increase after three wet-dry cycles. With the increase of the number of dry-wet cycles， the number of small pores in the compacted unsaturated loess obviously increases and the number of medium and large pores has a slight variation.