单轴压力下RST轻质土变形特性及其细观机理分析

通过无侧限抗压强度试验和细观试验,研究了废弃轮胎橡胶颗粒轻质混合土(RST轻质土)在单轴压力作用下的变形特性及其细观成因,得到了应力-应变曲线与材料配合比的关系以及有代表性的细观图片.无侧限抗压强度试验结果表明:RST轻质土的应力-应变曲线为软化型,可以被概括为压密、弹性变形、塑性变形、软化4个特征阶段.细观试验结果表明:在处于加载初期的压密阶段,最先发生变化的是试样内部的孔洞,这些孔洞在外荷的作用下有闭合的趋势,但不会完全消失;由外荷造成的裂缝的出现标志着塑性变形阶段的开始,外荷引发的裂缝最初会从试样内部原有的孔洞以及橡胶颗粒和水泥土的结合面上开展.试验结果还表明,土体的宏观现象是其细观结构变化的体现,废弃轮胎橡胶颗粒轻质混合土的细观孔隙裂缝发展情况可以解释其宏观应力-应变曲线的形态特征.

Deformation behavior and its meso-mechanism analysis of lightweight soil mixed with rubber chips of scrap tires based on unconfined compressive test

Based on the unconfined compressive strength tests and the mesoscale experiments, the deformation properties and meso-structure mechanism of lightweight soil mixed with rubber chips of scrap tires (RST for short) under uniaxial pressure were studied. The relationship between the stress-strain curves and ingredient proportions as well as the representative meso-images were obtained. The results of the unconfined compressive strength experiments indicate that the soil has softing stress-strain curves with 4 characteristic phases: compression phase, elastic deformation phase, plastic deformation phase and softing phase. The results of the mesoscale experiments indicate that at the compression phase with the initial stage of loading, the cavities inside the samples changes first and tend to be close under the action of external loads and do not completely disappear. The cracks caused by the external loads stand for the starting of the plastic deformation phase. The cracks start from the cavities and the joint surfaces between rubber chips and cement soil. The macroscopic phenomenon of the soil is the representation of change of meso-structure. The development of the meso-cracks of the lightweight soil mixed with RST can explain the shape characteristics of macro stress-strain curves.