植草沟专用堰的设计与率定研究

DESIGN AND ITS CALIBRATION OF SPECIAL TURTLES FOR GRASSING DITCH

植草沟是海绵城市建设中一种重要的转输设施,但现有的计量方法难以直接测定植草沟流量,因而提出利用薄壁三角堰,并通过设计一种与植草沟贴合的堰槽方式来测定植草沟的过流流量,使用此设施不仅可以监测植草沟进出口流量,还可以在不破环植草沟结构的前提下测定植草沟内任意一段的流量。采用直线边坡加圆弧底方式构建了非常规堰槽结构、直角三角形开口方式,实验率定了堰上水头与流量之间的曲线,并与既有公式进行对比。结果表明:相同堰上水头条件下,直角三角堰用既有公式计算出的流量值小于该堰槽方式下的实测值,且相对差值较大,实验范围内最大差值达25.9%,因此既有计算公式不能直接用于流量计算,而必须进行率定。通过率定拟合公式计算出流量与实测流量相对误差的绝对值在5%左右,计量精度能满足工程要求。

Grass-planting ditch is an important transfer measure in the construction of sponge city,and it is important in academics and engineering to monitor its flow rate,However,it is difficult to directly measure the flow rate of grass-planting ditch through the existing measurement methods.This paper proposed the use of thin-walled triangular rafts and the design of a kind of trough with grass-planting ditch to determine the flow.This facility could be applied not only to monitor the in- and out- flow of grass ditch,but also to determine the flow rate of any section of grass-planting ditch without breaking the structure of grass-planting ditch.In this study,an unconventional gutter structure and an orthogonal triangle opening method had been constructed using straight slopes and arc bottoms.The curve between the head and the flow rate of the crucible was determined and compared with the theoretical formula.The result showed that,in this trough method,the calculated value of the trigonometric formula was smaller than the measured value,and their relative error was large,The maximum of relative error was 25.9% in the experimental.It was suggested that the formula for the calculation of triangular angles couldn’t be directly used to calculate the flow rate in the guttering mode,and must be calibrated.The relative error between the measured flow and the measured flow rate calculated by the fitting formula between the upper head and the flow rate determined was about 5%.The measurement accuracy met the relevant regulations and engineering requirements.