龙潭沟水库溢流坝泄洪消能局部冲刷试验研究

采用几何比尺为1∶30的大比尺整体枢纽水工模型,根据重力相似准则,进行了龙潭沟水库溢流坝泄洪消能水力学试验研究。试验结果表明,设计洪水时,原设计方案及修改方案都不会对下游河床造成冲刷;下游河道水流平稳,流速分布均匀。校核洪水时,随着溢流坝过坝流量的增加,单宽流量增加坝面水深增大,原设计光滑溢流坝面沿程水流掺气消能效果欠佳,下游流速大、水流紊乱,挑流水舌下游造成严重冲刷,影响泄洪安全。通过方案修改优化,提出阶梯溢流坝台阶尺寸为0.90 m×0.72 m+连续挑坎方案新型消能形式,宣泄校核洪水时消能率较高,且下游河道水流平稳,流速较低且分布均匀,满足龙潭沟水库工程的安全泄洪。

Hydraulic experimental studies on the spillway of Longtangou reservoir

Based on a 1:30 large geometric scale for the hydraulic model， the hydraulic tests are made according to the gravity similarity criterion. The test results show that under the overall design flood， the original design and modification scheme will not cause the erosion of downstream river channel. Flow in downstream channel is flowing smoothly， and the velocity distribution is uniform. During the period of the check flood， the unit width discharge increases with the increase of flood discharge along the spillway. Air entrained energy dissipation effect reduces along the spillway of flow surface in the original design， which causes serious scour along the lower channel by the nappe and loads to the tunnel outlet channel blocked seriously. It will affect the safety of the tunnel during flood discharging. Through the scheme optimization modification， the ladder step size of 0.90 m×0.72 m with continuous flip bucket scheme is put forward. The energy dissipation is higher under the check flood condition， the nappe distance and the scour degree of the lower channel are reduced greatly， the downstream flow is flowing smoothly and the velocity distribution is uniform along the channel. The flow velocity in the lower channel is less than 2.80 m/s and meets the requirements of the safety flood discharge from the stepped overflow dam.