The most common type of diversion structure used in boulder streams is a trench weir. It is a simple structure built below the bed level of streams, and the top of it is covered with bottom rack. Bottom rack consists of bars of various shapes like circular, rectangle, T-shaped, etc. It is placed over the trench weir with a desired porosity to control sediment ingestion into trench. In this present study, T-shaped bars are used because sediment ingestion and maintenance in the bottom rack consisting of T-shaped bar shall likely too low as compared to the rounded bars and rectangular bars. As in previous studies, Garcia et al. (Water 10(1035):1–21, 2018a, Water 10(1699):1–21, 2018b) compared the blocking capacity of bottom intakes having circular bars with intakes having T-shaped bars, they claimed that circular bar is inefficient as compared to T-shaped bars. The present study is based on experimental investigation of trench weir consisting of T-shaped bars under free flow condition, and it was found that the coefficient of discharge decreases with an increase in clear spacing of rack, slope of bottom rack, specific energy of approach flow, Froude number and Reynolds number. An equation is also being proposed to calculate coefficient of discharge with a maximum error of ± 20%.

巨石流中使用的最常见的导流结构类型是沟堰。它是一种简单的结构，建在河床水平以下，顶部覆盖有底部搁板。底架由各种形状的条组成，例如圆形，矩形，T形等。它以所需的孔隙率放置在沟堰上，以控制沉积物向沟中的吸收。在本研究中，使用T形杆是因为与圆形和矩形杆相比，由T形杆组成的底架中的沉积物摄取和维持可能太低。与以前的研究一样，Garcia等人。（Water 10（1035）：1-21，2018a，Water 10（1699）：1-21-2，2018b）比较了带有圆棒的底部进水口与带有T形棒的进水口的阻塞能力，他们声称，圆形钢筋与T形钢筋相比效率低下。本研究基于自由流动条件下由T形杆组成的沟堰的实验研究，发现放电系数随着齿条净间距，底齿斜率和进近比能量的增加而减小。流量，弗洛德数和雷诺数。还提出了一个方程来计算最大误差为±20％的放电系数。