非均匀沙床面平衡浓度

根据近底非均匀沙交换的随机 力学模式首次从理论上建立起非均匀沙床面平衡浓度公式，将床面平衡浓度表示为起动、不止动和悬浮概率以及单步运动平均时间比B的函数关系。残差修正灰色系统模型和指数拟合关系用于悬移质平衡浓度竖向分布实测资料以获得床面平衡浓度值，据此确定理论公式中的参数B.床面平衡浓度计算与“实测”值比较结果令人满意，意味着本文提出的公式是合理的，可作为悬移质运动微分方程的底部边界条件。

Equilibrium bed concentration of non uniform sediment

Based on the stochastic mechanistic model for exchange of non uniform sediment near the river bed,a theoretical formula is developed for the equilibrium bed concentration of the kth fraction of non uniform sediment defined at the bed surface.The bed concentration is the function of incipient motion probability,non ceasing probability,pick up probability and the ratio of single step motion time to repose time.The result calculated from the proposed formula is in good agreement with the measured data.Therefore,the present formula can be used to the bottom boundary condition for the differential equation of suspended load motion.