坡积松散体稳定性模型试验研究

Study of model test on stability of colluvial slopes

云南西北部三江源高海拔、高深切地区,坡积松散体稳定性是公路边坡面临的主要问题之一,模型试验是研究松散体稳定性各影响因素最有效的手段。根据相似原理,设计模型试验的主要几何相似常数,采用一系列手段改造模型试验材料,使其达到材料强度、重度相似。一系列模型破坏条件真实再现现场坡积松散体的滑坡条件,试验结果分析对相关设计、施工和科研人员有较好的借鉴作用。模型试验材料从松散状态到较密实状态,开始破坏的自然坡角提高42%~100%,c值提高约50%~120%,值提高约6%~8%,密实状态提高,坡体的强度提高,相应坡体的稳定性提高,起始破坏的自然坡角也显著提高;降雨使坡体含水率提高近饱和时,充分软化的c值下降约70%,值下降约7%,表明雨水下渗软化是导致坡积松散体产生滑动的最根本、最直接的因素。模拟降雨的土体强度变化过程对松散体边坡稳定性研究有较好的参考价值。

The stability of colluvial slopes in high-altitude mountain areas,three rivers sources regions,northwestern Yunnan is one of the main problems in road construction.Model test is one of the most effective means for investigating the factors for the slope stability.Based on the theory of similarity and the definition of safety factor of the slope,a range of tools are used to transform the model test materials to reach the strength similarity requirements.A series of model tests were carried out,which reproduced the real conditions for the failure of colluvial slope.The model test results can give references for geotechnical designers and researchers.The slope angle when the slope fails increases by about 42%-100%,the cohesion increases by about 50%-120%,the internal friction angle increases by about 6%-8% when model test material changes from loose state to more dense state.The results show that when material density increases the strength increases and the slope stability increases;thus slope angle also significantly increases when slope fails.When water content of the material increases and the material is nearly saturated under rainfull,the cohesion decreases by about 70% and the internal friction angle decreases by about 7%.It is indicated that the material softening by infiltration is the most fundamental factor for the stability of colluvial slope.