水力插板透水丁坝坝头冲刷深度规律初探

Preliminary Exploration on the Law of Jetty Head Scour Depth of Hydraulic Flashboard Permeable Spur Dike

水力插板透水丁坝的坝头局部冲刷严重影响着水力插板的稳定性和安全性。采取单因素控制变量的方法进行室内动床试验,探索了坝头冲刷坑深度与模型沙粒径、束窄度、流量、水力插板透水率、丁坝挑角之间的关系。结果表明:当模型沙粒径从0.058 mm至0.138 mm增大138%时,坝头冲刷坑深度从9.2 cm至5.7 cm减小38%;当丁坝束窄度从0.08至0.42增大425%时,坝头冲刷坑深度从5.3 cm至9.2 cm增大74%;当流量从10.28 L/s至16.03 L/s增大56%时,坝头冲刷坑深度从6.5 cm至9.6 cm增大48%;当水力插板透水率从0增大至80%时,坝头冲刷坑深度从8.9 cm至2.1cm减小76%;当挑角θ小于90°,从30°至90°增大200%时,坝头冲刷坑深度从6.5 cm至9.0 cm增大38%;当挑角θ等于90°时,坝头冲刷坑深度达到最大值;当挑角θ大于90°,从90°至150°增大67%时,坝头冲刷坑深度从9.0 cm至7.1 cm减小21%。详细分析了模型沙粒径、束窄度、流量、水力插板透水率、挑角的变化对坝头冲刷坑深度影响的机理。

Local scour of jetty head of hydraulic flashboard permeable spur dike seriously affects the stability and safety of hydraulic flashboard. Through the method of single factor to experiment,the paper explored the relationship between the depth of jetty head scour pit and the size of model sand particle,spur dike narrow rate,discharge,water permeability of hydraulic flashboard and layout angle. The results show that when the size of model sand particle increases by 138%,the depth of jetty head scour pit is decreased by 38%; when the spur dike narrow rate increases by 425%,the depth of jetty head scour pit is increased by 74%; when the discharge increases by 56%,the depth of jetty head scour pit is increased by 48%; when the hydraulic flashboard permeable rate increases by 80%,the depth of jetty head scour pit is decreased by 76%; When θ is less than 90° and increases by 200%,the depth of jetty head scour pit is increased by 38%. When θ is equal to90°,the depth of jetty head scour pit is increased to the maximum. When θ exceeds 90° and increases by 67%,the depth of jetty head scour pit is decreased by 21%. Furthermore,it also analyzed and explained the mechanism of the size of model sand particle,spur dike narrow rate,discharge,water permeability of hydraulic flashboard and layout angle to the influence of the depth of scouring pit of jetty head.