边界条件对自然河流形成及演变影响机理的实验研究

运用自然模型法,采用清水冲刷成功地塑造了室内天然小河。实验研究了不同的初始河流几何边界条件以及水流条件对河流演变的影响。研究发现流量对河流展宽幅值影响最大。水流入射角的大小与河流展宽幅度及河流弯曲度的变化没有必然的联系,30°入射角时小河的河流展宽及弯曲度变化最明显。入射角对河流演变的作用只是短期的,且在演变初始阶段影响较大。受初始边界条件的影响,河流向下游演变具有滞后性及曲率变化的传递性等特点。本文最后分析了河流演变过程中的泥沙分选现象。

Experiment on influence mechanism of boundary conditions to the formation and evolution of natural river

Using the natural model method,an indoor natural river has been successfully portrayed with the scouring water.The experiment includes the study of the influence of different initial river geometric boundary conditions on river channel evolution process and different flow conditions.Studies reveal that flow is mostly influence to river stretcher amplitude.There are no necessary relationships among the size of the inflow angle and river’s stretcher range and the changes of river bend degrees,when the inflow angle is 300,changes of river width and curvature are the most obvious.The inflow angle affects the river evolution in a short-term and has a greater impact in the initial stage of evolution.Subjecting to initial boundary conditions,river’s evolution downward is lag and transitivity of curvature changes.Finally,this paper analyzed the sediment sorting phenomena in the process of river evolution.