某中小河流岩基河段冲刷深度的计算研究

Calculation of the Scour Depth of the Rocky Reach of a Medium and Small River

山区中小河流地质条件复杂、河道纵坡比降大,常出现河床的岩基冲刷破坏现象。针对现行堤防工程设计规范中,尚无明确的岩基冲刷深度计算方法,结合工程实例,通过原型观测、工程类比,提出了堤防工程岩基冲刷计算方法,并将该方法应用于工程实例。计算结果表明,平流段一般冲刷深度和局部冲刷深度与计算结果相近且整体偏小,符合冲刷的时间效应与现状洪峰流量;跌流段计算结果比原型观测结果明显偏小,说明GB 50286-2013《堤防工程设计规范》中公式D.2.2-1不再适用于跌流冲刷模式,而采用水跃消能理论公式的计算结果更符合原型观测结果,具有较高的安全储备。

The geological conditions of small and medium-sized rivers in mountainous areas are complex,and the longitudinal slope gradient of the river is high.Therefore,the rock foundation erosion and scour damage of the river bed often occurs.In view of the fact that there is no calculation method for rock foundation scour depth in the current design specifications for design of levee project,combined with engineering examples,through prototype observation and engineering analogy,a calculation method for rock foundation scour of levee project is proposed,and the method is applied to engineering practice.The calculation results show that the general scour depth and local scour depth of the constant-flow section are similar to the calculation results,and the overall scour depth is relatively small,which is in line with the time effect of scour and the current peak flow;Yet,the calculation result of down flow section is significantly smaller than the prototype observation results.Therefore,the formula D.2.2-1 in the Code for Design of Levee Project is no longer applicable to the down flow scour mode,and the calculation results using the hydraulic jump energy dissipation theory formula are more in line with the prototype observation results and have a higher safety reserve.