水石流起动的流量控制研究

Flow Control of Water-stone Flow Start

沟谷中水石流的发生不仅需要一定的坡度,还需要一定的水深。对于确定的沟谷,其断面形式是一定的,通过研究水石流发生时层移运动厚度与沟谷中所需最小水深的相关关系,并利用均匀流的水力学模型理论分析水深与流量的关系,可建立沟谷中层移层厚度与沟谷中水流流量关系,从而确定水石流发生时层移运动厚度与所需流量的关系。通过运用数学推导的方法,得出汇水动力区接触松散堆积物前的均匀流水深h水与水石流层移运动厚度z的关系式,表明在特定沟谷坡度和堆积物特性一定的条件下,水深是决定松散堆积物转化为层移层厚度大小的动力关键因素,纵坡坡度、沟谷断面形式以及横坡系数大小都会对水深产生影响。随着沟谷坡度的增大,水石流起动所需的清水水深变小。基于这理论分析结果,工程上可通过流量控制的方法,实现最低限度的分流,避免松散堆积物整体性的层移运动,防止水石流的发生。

The occurring of water-stone flow （ belonging to dilute debris flow） in the valley not only needs a certain slope, but also a certain amount of water depth. The section form is certain for a certain valley. Through studying the relationship between the thickness of sheet-flow layer and required minimum water depth in the valley when the water-stone flow occurs and analyzing the relationship between water depth and flow using the uniform flow theory of hydraulic model, it will find the relationship between the water flow and the thickness of sheet-flow layer in the val- ley . Then, it will determine the relationship between the required water flow and the thickness of sheet-flow layer for the occurrence of water-stone flow in the valley. By using the method of mathematical deduction, it obtains the relationship between the water depth h, of the uniform flow in dynamic area catchment before loose deposits and the thickness of sheet-flow layer z. It shows that the water depth is the key dynamic factor which dominates how much loose deposits becomes sheet-flow under the condition of specific gully slope and certain characteristics of deposits. The longitudinal slope, the form of cross section and the cross slope coefficient will have an impact on water depth. With the increasing of the gully longitudinal slope, the water depth needed for water-stone flow start becomes shallo- wer. Based on results of the theoretical analysis, it can achieve minimum bypass flow with the method of flow con- trol in engineering. Then it will avoid the whole sheet-flow of loose deposits and prevent the occurrence of waterstone flow.