斜交桥墩局部冲刷坑形态试验研究

Study on the Morphology of Local Erosion in Oblique Piers

为研究斜交桥墩在多沙河流上的局部冲刷问题,利用1∶100正态模型水槽对不同斜交角度长方体圆墩进行了系列试验,对桥墩在不同水流强度、斜交角度条件下的冲刷坑形态进行了系统观测和分析。结果表明:斜交桥墩冲刷坑的几何特性与正交桥墩存在较大区别,当单宽流量为10 m3/(s·m)、斜交角度为15°以上时,桥墩会出现共轭冲刷坑;当桥墩斜交时,背水侧会出现顺时针旋涡水流下降区,迎水侧墩尾处受水流顶冲出现局部冲刷坑;桥墩局部冲坑深度、体积、范围等要素均随水流强度及斜交角度的增大而增大,墩尾冲刷坑深度约为墩前的0.7倍,桥墩冲刷坑面积与桥墩投影面积比的最大值为32.4;水流强度较小时规范公式计算值与试验值较吻合,水流强度较大时规范公式计算冲深小于试验值,二者比值为0.66～0.92。

In order to study the local scour problem of the inclined bridge pier in a multi-sediment river, a series of experiments were carriedout on oblique piers of different oblique angles by using 1 ∶ 100 normal model flume. The system observation and analysis of the scoured pitform under the angle of different flow intensities of the bridge pier were carried out. The results show that there is a big difference between thegeometric characteristics of the punching hole and the orthogonal piers. When the unit discharge is 10 （m^3/ s） / m and the skew angle is notless than 15°, the bridge pier will appear the conjugate erosion pit. When the bridge pier is inclined, the backwater side will appear clock-wise vortex flow drop zone and the water head will erode a hole at the end of the pier. The volume range of local scour depth of bridge pier in-creases with the increase of water flow intensity and oblique angle. The depth of the eroded hole at the pier tail is about 0.7 times deeper thanthat of the front of pier. The maximum value of the area of the bridge pier and the projected area is 32.4. When the flow intensity is smaller,the calculated value of the formula is consistent with the test value. When the flow intensity is larger, the standard calculation is less than thetest value and the proportionality of the two is about 0.66-0.92.