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| Differentiation characteristics and mechanism of hydraulic erosion of soil-rock mixtures with different rock content |
| YANG Zhongping1，2，3，LI Yonghua1，LI Shiqi1，LIU Haoyu1，GAO Yuhao1 |
(1. School of Civil Engineering，Chongqing University，Chongqing 400045，China；2. Key Laboratory of New Technology for Construction of Cities in Mountain Area of Ministry of Education，Chongqing 400045，China；3. National Joint Engineering Research Center of Geohazards Prevention in Reservoir Area(Chongqing)，Chongqing 400045，China)
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Abstract Hydrodynamically induced colluvial landslide is one of the main geological disasters in southwest China. It is significant to investigate the erosion differentiation mechanism of soil-rock mixtures for revealing the landslide mechanism in depth. The rock content is the most important factor affecting the erosion differentiation characteristics of soil-rock mixtures. Based on the seepage erosion tests of soil-rock mixtures with different rock content，the erosion differentiation characteristics and mechanism of soil-rock mixtures are revealed. The results show that there are four random states in the process of seepage erosion of soil-rock mixtures：erosion intensification，erosion mitigation，internal block structure reorganization and erosion stability. The rock content has a significant effect on the erosion differentiation characteristics. The permeability coefficient of soil-rock mixture increases at first，then decreases subsequently，and then increases again with the increasing rock content，and the lowest value is observed at the rock content of 60%，which was less than 1×10－2 cm/s and cause a slight fluctuation. Whereas，the permeability coefficient of soil-stone mixtures at a high rock content is nearly unchanged before and after seepage，with a change rate less than 10%. The amount of erosion increases with the increasing hydraulic gradient. On the basis of change of erosion amount，the seepage erosion is divided into three stages：violent erosion，slow erosion and stable seepage stage. The critical hydraulic gradient decreases with increasing rock content. The rock content affects the permeability of the soil-rock mixtures by affecting the filling form of the soil-rock structure，and the full-filled structure has the best impermeability，which provides ideas and references for revealing the mechanism of hydraulic instability of the colluvial slope.
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