环翼式防冲板对圆端形桥墩局部冲刷试验及水力特性

由于传统桥墩冲刷防护措施的局限性,引入新型防冲装置-环翼式防冲板,对圆端形桥墩冲刷进行防护,通过减小下降水流改变桥墩周围水流结构,主动降低了下降水流对桥墩的冲刷。为探究环翼式防冲板对圆端形桥墩局部冲刷的防护作用,采用3种比例圆端形桥墩、3种环翼式防冲板安装位置进行物理模型试验,对圆端形桥墩周围的冲坑特征、垂向流速、垂向紊动强度、紊动切应力等水力要素进行研究。结果表明:安装环翼式防冲板后,3种圆端形桥墩冲刷程度均减小,中圆端形桥墩冲刷减小幅度最大,冲坑体积减小率为30.0%;中圆端形桥墩安装环翼式防冲板后,墩前垂向流速减小为0.039m/s、垂向紊动强度减小为0.025m/s;防冲板上垂面紊动切应力增大,板下垂面紊动切应力减小。试验结果表明环翼式防冲板能够减小桥墩的局部冲刷,具有很高的实用价值。

Resistance capability and hydraulic characteristics of ring-wing plates against local scour of round-ended piers

Because of the limitations of traditional anti-scour measures for piers, we adopted a new device, ring-wing plate, to protect round-ended piers against scour. The plate changes the flow structure around the pier by reducing the descending flow, and thus reduces the scour of the pier by the descending flow. To study the protective effect of the ring-wing plate on round-ended piers against local scour, we conducted physical model tests with 3 sizes of round-ended piers and 3 installation positions of the ring-wing plate, and analyzed such hydraulic elements as the characteristics of the scour pits around the piers, vertical flow velocity, vertical turbulence intensity, and turbulence shear stress. The results showed that the scour of the 3 types of piers was all reduced, and the medium-sized piers had the greatest reduction in scour among the 3 sizes, with a 30% reduction in the volume of the scour pits. After the ring-wing plate was installed around the medium-sized piers, the vertical flow velocity before the piers declined to 0.039m/s and the vertical turbulence intensity to 0.025m/s; the turbulence shear stress above the plate increased while the turbulence shear stress under the plate decreased. The results indicated that the ring-wing plate can reduce the local scour of piers and has a high practical value.