冻融循环作用下含“架空”结构土石混合体边坡变形机理试验研究

Deformation Mechanism of Soil-rock Mixture Containing Macropore Structure Based on Freeze-thaw Test

含"架空"结构土石混合体是一种有别于岩体和土体的特殊地质材料,广泛分布于我国西南地区,其组成结构及变形特性是崩塌、滑坡和泥石流等地质灾害频发的主要诱因.目前的研究成果对其力学特性及变形破坏机理的解释远远不够,以青藏高原多年冻土区土石混合体为研究对象,从含"架空"结构土石混合体的形成结构、分布特征及变形特性入手,采用现场调查、采样分析、室内试验及试验结果分析等技术手段,针对含"架空"结构层的土石混合体的变形特征开展研究.研究结果表明,土石混合体边坡失稳主要原因是冻融循环作用下岩土介质力学结构的破坏以及富冰层对补给水的滞留作用降低了上覆岩土体与富冰层的摩擦系数."架空"结构不仅具有阻滞环境与下伏岩土体之间热交换的作用,并且作为泄水通道,改变了上部补给水的运移途径,同时"架空"结构也是富冰层的良好发育场所.研究结果对含"架空"结构土石混合体导致的地质灾害的预测、预防及控制提供理论依据.

Soil-rock mixture containing macropore structure（SRMCMS）widely exists in south and western China.The SRMCMS exhibits the complex structural characters and mechanical performance. The SRMCMS is the mainly factor that induces the geological disaster such as collapse,landslide and debris flow. Currently,the formation mechanism and the long-term deformation performance of the SRMCMS is not well understood. Taking the permafrost region of the Tibetan Plateau as a research example,a synthetic method,which includes the field investigation,theoretical analysis,laboratory test and numerical simulation,is employed in this paper. The research shows that the main reasons of soil rock mixture slope instability are the mechanical structure destruction of rock and soil under the action of freeze-thaw cycle,and the make-up water retention of rich ice layer which reduced the friction coefficient of overlying rock and rich ice layer. Macropore structure not only has the effect of heat exchange between the environment and the underlying block of rock and soil,and as the discharge channel,indirectly to aquifuge,but also be a good place for the development rich ice layer at the same time. The results provide a theoretical basis for the prediction,prevention and control of geological hazards caused by the soil-rock mixture containing ＂overhead＂ structure.