重塑黄土冻融过程抗剪强度劣化特性试验研究

Experimental research on shear strength deterioration of remolded loess under the freezing-thawing cycle

以西安Q3重塑黄土为研究对象,对经受冻融作用后的黄土试样开展电镜扫描和直剪试验,研究重塑黄土冻融过程微观结构和剪切强度变化规律.结果表明:重塑黄土体冻融过程微观结构发生显著变化,主要表现在冻融过程中骨架颗粒间冰晶生长导致的土体大骨架颗粒数量显著减少.冻融过程土体表面结构特征发生改变,其破坏程度与土体初始条件相关,含水率越高,冻融周期越多,土样表面特征破坏越明显.重塑黄土粘聚力随冻融周期增加以指数规律衰减,随含水率增加呈线性减小趋势,随千密度增加呈线性增加趋势.内摩擦角冻融过程变化规律不明显.基于室内试验数据,最终提出了重塑黄土粘聚强度劣化模型.

The influence of freeze-thaw cycle on the microstructure and strength of Xi＇an Q3 remolded loess was studied by SEM and direct shear tests. The results show that during the freeze-thaw process, the growth of ice crystal results in obvious destruction of large particles aggregate. Freezing-thawing has caused more serious damage on the surface structure of soil with the increase of initial water content and freezing-thawing times. The cohesion of remolded loess exponentially decreases during the freeze-thaw process. The cohesion linearly decreases with the increase of water content ,and linearly increases with the dry density increasing. The internal friction angle of remolded loess has no obvious change rule during the freeze-thaw process. Based on the indoor test resul ts,a cohesion strength deterioration model of remolded loess was finally established.