EVOLUTION PRINCIPLE OF DEBRIS FLOW CONFLUENCE WITH MAIN RIVER

摘要

In this paper, relative water depth, deposit volume, deposit ratio and deposit depth of debris flow at the confluence area were experimentally studied. Relative water depth, which was caused by the confluence of debris flow, was found to increases with the increasing of the discharge ratio and the confluence angle. As deposit principle of debris flow behind the confluence port was studied, deposit volume was found to increase with the increasing of lateral discharge when the confluence angle was 30°, 60° and 120° respectively. And it decreased with the increasing of discharge of debris flow at the angle of 90°. When the confluence angle was 30° and 120°, it got an uphill-sinusoid relationship between the deposit volume and discharge ratio. And it became a liner curve at 60°. Though the reason was different, the deposit volume of 60° and 120° were almost equal. When the confluence angle was 90°, it became a downhill-sinusoid relationship between the deposit volume and discharge ratio. And the deposit volume was the smallest at the angle. Meanwhile, deposit ratio decreased with the increasing of total discharge when the confluence angle was 30°, 60° and 120°, and increased at the angle of 90°. Deposit ratio changed with the discharge ratio as a parabola relationship at the angle of 30°, 60° and 120°. And it was a contrary parabola relationship at the angle of 90°. It got the maximum value when the discharge ratio was 0.5 at the confluence angle of 30°, 60° and 120°. And it got a minor value at the same discharge ratio when the confluence angle was 90°. Both average and maximum deposit depth got the maximum value when discharge ratio was 0.5. When debris flow entered Main River along downstream direction, the larger confluence angle, the larger maximum value of the deposit depth was. The maximum value of deposit depth, however, was the same at confluence angle of 120° and 30°.