拦沙坝调节泥石流拦挡与输移性能的试验研究

EXPERIMENTAL STUDY OF REGULATING BARRAGE AND TRANSPORTATION PROPERTIES OF DEBRIS FLOW BY SILT-TRAP DAM

拦沙坝是泥石流防治措施中的一种重要拦蓄拦挡工程,在野外调查的基础上,结合防护体系配置优化的新思路展开试验研究。在室内二维水槽模型试验中,通过改变泥石流容重、一次过程体积总量和模型坝的开孔率等控制参数,得出泥石流性能在过坝前、后的变化规律。试验结果表明:(1)回淤坡度随泥石流容重、一次输移体积总量的增大和开孔率的减小而增大。泥石流容重越小,输移体积总量和坝身开孔率对坡度的影响越大。(2)当泥石流一次过程输移总量不超过拦沙坝库容时,开孔率2.2%时的流量变化量为6.6%时的2倍左右。(3)在相同的排水孔过流方式下,可用二次式来拟合物料容重与容重比值的关系。由该拟合式可推出容重为15.67 kN/m3时,容重变化程度最大。(4)引入D50比值作为表征拦沙坝分选泥石流能力的参数,比较泥石流过坝时的颗粒变化情况,稀性泥石流经过拦沙坝时,其"拦粗排细"作用最突出。

Silt-trap dam is an important debris flow preventive measure with a large cubage. According to the forms and circs of the dams summarized and a new notion of the system collocating optimization, the experiment on regulating properties of debris flow by the silt-trap dam has been performed. In the experiment, bulk density, gross and the rate of the drainage hole are changed to analyze the property variation law of debris flow. The experimental results show that： （1） The gradient of intercepted sediments increases with the increase of bulk density and gross of debris flow, and the decrease of rate of drainage hole. The bulk density is smaller, the effects of the gross and rate of drainage hole on the gradient are larger. （2） When the gross of the debris flow is less than the cubage, the value of the flux changing with a drainage hole rate 2.2% is twice to that with a rate 6.6%. （3） Under the same over-current of the drainage hole mode, the former bulk density gets a square formula relation with its ratio to the latter. With the formula, we find that when the bulk density is 1.567 kN/m3, the change of bulkdensity before and after experiment is the biggest. （4） The ratio of Ds0 between before and after the experiment is proposed to scale the selection property of the dam and compare the change of grain diameter. The dam gets the most evidently effect of leaving the coarse grain and passing the fine grain when the watery debris flow passes through the dam.