圆柱桥墩局部冲刷机理试验研究

为进一步探索圆柱桥墩局部冲刷机理,分别从桥墩附近水流流速分布特性、桥墩冲刷特性以及冲刷与流速相互关系对圆柱桥墩顺水流向不同布置方式的局部冲刷水力学特征进行了模型试验研究.结果表明:两排10桥墩顺水流(桥墩轴向与水流方向夹角分别为90°,60°,30°,0°)均匀布置时,桥墩轴向与流向夹角越小,流速在桥墩上下游紊动越小,对下游影响范围越大,且流速越大,冲刷深度和范围越大.顺水流布置0°夹角时,冲刷程度最小,在相同流量下,冲刷稳定历时最短;垂直布置(90°夹角)时,冲刷程度最严重,所需冲刷稳定历时最长,且随着流量的增大,桥墩墩前冲刷坑最深位置逐渐向水槽中间偏移.

Experimental studies on local scour mechanism of cylinder bridge piers

The model experimental studies on the flow and local scour hydraulics characteristics around piers are conducted considering flow structure,velocity distribution,changes in the water surface profile,scouring terrain characteristics,and the relation between scouring and velocity,and so forth,for further studying scour mechanism of cylinder bridge piers.The results show that the smaller the velocity change in the upstream and downstream,the greater the incidence in the downstream;and the greater the velocity,the greater the scour depth and incidence.In the studies,we adopted 10 piers,in two rows,designed four different pier arrangement patterns,namely,the angle(90°,60°,30°,0°) between the axial direction of bridge piers and the flow direction.The scouring is the slightest and the scouring steady time is the shortest under the condition of the same discharge when the included angle is 0° between the axial direction of bridge piers and the flow direction.The scouring is the most serious and the time is the longest when the included angle is 90°.And the deepest location of the scour hole in front of piers deviates to the middle of the flume gradually with the discharge increasing.