降雨条件下坡面细沟侵蚀模型及临界坡度研究

Research of Rill Erosion Model and Critical Slope Gradient during Rainfall

分析了坡面侵蚀影响因素,采用水力学计算公式,建立降雨条件下,坡面细沟侵蚀模型。对坡面松散颗粒启动和土块启动进行分析,得出了坡面侵蚀临界水深条件。并对侵蚀速率及其影响因素进行探讨,得出当侵蚀速率大于零时,坡面侵蚀能力随着坡度的增大而增大,当侵蚀速率小于零时,坡面抗侵蚀能力随着坡度的增大先增大后减小,存在一个临界坡度θm,临界坡度一般在7°-24°之间,受内摩擦角的影响显著,随着内摩擦角的增大而增大。同时,基于侵蚀速率、侵蚀方式和临界坡度,将坡面划分为强烈侵蚀区、稳定侵蚀区和弱侵蚀区三个阶段,从力学的角度,揭示了坡面演化过程中的一些现象。

We analyze the effective factors of slope erosion and establishes slope rill erosion model during rainfall,by using hydraulics calculation formula. It gets the critical water depth conditions of slope erosion after analyzing the incipient motion of loose granular and clod on the slope. After the discussion of the influence factors of erosion rate,we draw conclusions that slope erosion ability improves with increasing of slope gradient when it is greater than zero. And if it is less than zero,that anti-erosion ability improves firstly,and decreases afterwards.There is a critical slope gradient（ θm） from 7° to 24°,influenced by internal friction angle significantly,increasing with increasing of internal friction angle. We can divide slope into three stages with the intensities of strong erosion,stable erosion,and weak erosion,according to erosion rate,erosion pattern and critical slope gradient. Meanwhile,it explains the phenomenon of slope evolution from the viewpoint of mechanics.