不同地表粗糙度坡面流水力学特性试验研究

Experimental study on hydraulic characteristics of overland flowunder different surface roughness

为进一步探明坡面流水力学特性,通过室内定床放水冲刷试验,研究了不同流量和坡度下不同粗糙度(0.2~0.6 mm、0.6~1 mm、1~1.4 mm、1.4~2 mm、2~3 mm粒径和光滑对照组)下垫面的坡面流水力学特性。结果表明:下垫面粗糙度的增加减缓了坡面流流速,增大了水深,且流速和水深均与流量、坡度和粗糙度因子呈良好幂函数关系;雷诺数在对照组达最大值,粗糙度的增加使流型趋于缓流;阻力系数随粗糙度呈正势变化,其与流量、坡度、粗糙度因子的幂函数回归关系较好;计算径流剪应力与实测径流剪应力在对照组下垫面的关系良好,粗糙度增加对实测径流剪应力的增加有一定影响。研究成果对深入认识土壤侵蚀机理和坡面侵蚀防治具有重要意义。

To further explore the law of hydraulic properties of overland flow,the hydrodynamic characteristics of overland flow under different flow rates and slopes with different roughness(0.2~0.6 mm,0.6~1 mm,1~1.4 mm,1.4~2 mm,2~3 mm particle size and smooth control group)were studied by the indoor fixed-bed water scouring test.The results show that the increase of the underlying surface roughness slows down the overland flow velocity and increases the water depth.The flow velocity and water depth are well related to the flow,slope,and roughness factors as a power function.The Reynolds number reaches the maximum value in the control group,and the flow pattern tends to be slow flow with increasing roughness.The resistance coefficient positively changes with roughness and is in a good regression relationship with the power function of flow,slope,and roughness factors.The calculated runoff shear stress is well related to the measured runoff shear stress on the smooth underlying surface,and the increase of roughness has a certain effect on the increase of measured runoff shear stress.The results are significant for a deeper understanding of soil erosion mechanisms and slope erosion control.