不同密度砒砂岩风化物坡面水蚀机理试验研究

Experiments on water erosion mechanism of weathered Pisha sandstone slope with different densities

为研究砒砂岩风化物坡面水蚀机理,以期对鄂尔多斯水土流失治理提供数据参考,采用降雨模拟系统进行不同雨强、不同密度下降雨侵蚀试验,用直剪仪测得密度为1.7 g/cm^3砒砂岩风化物的黏聚力和内摩擦角,揭示了各密度坡面入渗产流及侵蚀特点的成因.结果表明:密度为1.7 g/cm^3的坡面稳渗率随雨强的增大而增大;对于1.5 g/cm^3的坡面侵蚀量对入渗速率的敏感率最高,1.6 g/cm^3的坡面侵蚀量对累积入渗深度的敏感率最高,而1.7 g/cm^3的坡面侵蚀量对产流量的敏感率最高;抗剪强度和侵蚀量的时程曲线呈负相关并有一定的对应性.从直剪试验和敏感度分析的角度均表明造成1.7 g/cm^3坡面侵蚀的主因是水流冲刷.

In order to study the water erosion mechanism of weathered Pisha sandstone and provide data reference for soil erosion control in Ordos,rainfall erosion experiments under different densities and rainfall intensities were carried out by using rainfall simulation system.The friction angle and cohesion of weathered Pisha sandstone with a density of 1.7 g/cm^3 were measured by a direct shear apparatus.For each slope with a particular density,the causes of infiltration runoff and erosion were revealed.The results show as follow:For the slope with a density of 1.7 g/cm^3,the steady infiltration rate increases with increasing rain intensity.For the slope with a density of 1.5 g/cm^3,the sensitivity of erosion due to infiltration rate is the highest.For the slope with a density of 1.6 g/cm^3,the sensitivity of erosion due to cumulative infiltration depth is the highest.For the slope with a density of 1.7 g/cm^3,the sensitivity of erosion due to runoff is the highest.The time-history curves of shear strength and sediment have a negative correlation.From the perspective of direct shear test and sensitivity analysis,the main cause of the erosion of 1.7 g/cm^3 weathered Pisha sandstone slope is flow scouring.