含竖向杆件的半圆形明渠糙率研究

TBM掘进机轨道常采用工字钢支撑,明渠底部设置工字钢后会降低其过水能力。为了定量研究明渠底部设置工字钢后对其糙率的影响,引入了等效水力参数的概念,对工字钢产生的等效附加糙率进行了理论分析。此外,结合某实际工程,通过模型试验研究,测量了设有工字钢的半圆形明渠在不同流量下的水深,采用假定糙率试算法、逐段计算糙率法对其综合糙率进行了计算分析。研究结果表明,建立的"糙率条带计算法+等效附加糙率计算法"得到的综合糙率值与模型试验值吻合良好,可采用理论计算方法估算半圆形明渠底部设置竖向杆件后的综合糙率。

Roughness Coefficient of Semicircle Open Channel with Vertical Bars

Tunnel-boring machines (TBM) are usually supported by Ⅰ-shaped beams which would reduce the drainage ability of open channel.To investigate the influence of Ⅰ-shaped beams on the roughness coefficient of the open channel,theoretical analysis on the equivalent additional roughness coefficient produced by Ⅰ-shaped beams was conducted by introducing the concept of equivalent hydraulic parameters.In addition,the water depth of semicircle open channel with Ⅰ-shaped beams under different flow rates was measured in a model test of a practical project,and the overall roughness coefficient of Ⅰ-shaped beams section was calculated through assumed trial method and piecewise average method.Results show that the theoretical values calculated by strip method combined with equivalent additional roughness coefficient method agree well with the test values.In conclusion,the roughness coefficient of open channels with vertical bars can be preliminarily estimated by theoretical calculation methods presented in this paper.