沿河公路路基冲失水毁机制

Collapse Formation Mechanism of Subgrade for Mountainous Highway along River

沿河路基冲失水毁是路基岩土体抗冲失能力与路基近壁水流冲失作用相互对抗的宏观表象。以路基岩土体起动切应力量化路基抗冲失能力,以近壁水流切应力量化河道水流对路基的冲失作用,通过二者大小对比计算路基冲失水毁。从微观紊流力学分析沿河路基冲失水毁的营力机制或动力来源,认为微观紊流漩涡是沿河路基冲失的基础,宏观次生环流、主流顶冲等是沿河路基冲失的助动力。从微观泥沙运动力学出发,采用水动力模型计算沿河路基冲失宽度。根据路基冲失宽度将沿河公路冲失水毁灾情等级分为四级,并提出了对应的路基冲失水毁抢修工作建议。

The washout damage of subgrade along river is macro representation for counteraction between anti-wash ability of subgrade material and wash ability of flood water near subgrade. Take starting shear stress of subgrade material to quantify anti-wash ability of subgrade along river,and take water shear stress to quantify wash ability of flood water near subgrade,calculate the subgrade flood washout through the comparison between them. Analysing the washout force mechanism from micro turbulent mechanics,form the idea that micro turbulent vortex is the foundational force for subgrade washout and auxiliary force including macro secondary circulation flow and rush force of mainstream. Calculate the subgrade washout width by hydrodynamic model from the view of micro sediment movement mechanics. Classified the flood washout disaster result into four levels according to the subgrade washout width,and proposed the corresponding repair advices for subgrade washout disaster by flood.