集中水流下土石混合崩积体坡面侵蚀水动力特征试验研究

Experimental Study on Erosion Hydrodynamic Characteristics of Concentrated Flow on Soil-rock Mixed Colluvial Deposit Slopes

为了探究土石混合崩积体坡面侵蚀的水动力学机理,采用室内放水冲刷试验,研究了不同流量(2,4,8,16L/min)和坡度(10°,20°,30°,40°)条件下4种土石混合崩积体(0,20%,40%,60%砾石质量百分数)坡面侵蚀的水动力学特征。结果表明:(1)在小坡度和小流量条件下,侵蚀率随砾石含量的增大而减小;当流量或者坡度增大时,侵蚀率随砾石含量的增加呈先减小后增大的规律;各土石混合物侵蚀率均能用坡度和流量的二元幂函数来表达。(2)水流剪切力、水流功率和单位水流功率与侵蚀率均呈线性函数关系,其中水流功率和水流剪切力可优先作为模拟土石混合崩积体坡面侵蚀的水动力学参数。(3)可蚀性参数及临界侵蚀动力随着砾石含量的增加而增加。研究结果可为进一步深化认识崩积体侵蚀机理提供参考。

In order to study the hydrodynamic mechanism of soil erosion on earth-rock mixed colluvial deposit slopes,scouring tests were conducted in the laboratory.In the tests,four the gravel contents（mass content）（0,20%,40% and 60%）,four flows（2,4,8 and 16 L/min）and four slope gradients（10°,20°,30°and40°）were set.Results showed the following：（1）Soil erosion rate decreased with the increasing of gravel content when the slope gradient or flow was low,while when the flow or slope gradient increased,erosion rate first decreased and then increased with the increasing of gravel content;erosion rates of different earth-rock mixtures could be expressed by power function of slope and flow.（2）Flow shear stress,stream power and unit stream power were all linearly related to erosion rate,while by comparison,shear stress and stream power were the optimal hydrodynamic parameters to simulate the erosion process on the earth-rock mixed colluvial deposit slopes.（3）Soil erodibility parameter and critical erosion force both increased with the increasing of gravel content.These results of this study could provide a reference for further understanding the erosion mechanism of colluvial deposit.