官地水垫塘底板泄洪振动响应特性研究

利用官地水垫塘底板泄洪振动响应原型观测成果,分析了不同泄洪工况下底板振动强度的分布特征,同时应用现代谱分析方法,从频域的角度分析了底板泄洪振动的频域特征,并研究了不同泄洪工况及流量对底板振动特性的影响,以及各测点的相关性。结果表明,在官地水电站底流消能的情况下,位于消力池内前段(坝前0+149m)这一区域的板块振动响应最为剧烈,之后沿程减弱。水流的不对称流动和摆动,引起底板不同区域的板块振动强度分布规律产生显著差别。正常运行下的水垫塘底板是在水流荷载作用下的随机受迫振动,各测点的振动相关性较好,底板整体性也较好,且优势频率非常稳定地分布在0.6～1.7Hz之间。水垫塘内涡旋尺度较大,底板振动本身有着很好的相似性和明显的同步性。随着泄洪流量的增大,正常运行下的底板振动强度平稳增强,优势频率缓慢下降,且当泄流量高于1 500m3/s后,优势频率随泄流量增大而下降的速度趋于缓慢,并最终趋于稳定。

Vibration Response Characteristics of Slabs in Plunge Pool of Guandi Hydropower Station

Based on the prototype observation results of dynamic displacement response from plunge pool slabs of Guandi hydropower station, the characteristics of vibration strength distribution in slabs were analyzed under different spillway conditions. The dominant frequency of vibration was studied using the modern spectral analysis method. Then the influence of spillway condition and discharge on the characteristics of vibration distribution in plunge pool slabs was analyzed, together with the correlation of the vibrations. The results show that the strongest vibration response occurs in the front (0+149m before dam) and decreases along the way. The asymmetry of water flow causes highly unequal distribution of vibration strength in slabs of different areas. Under normal operation, the plunge pool slabs vibrate randomly forced by flow load, with good correlation and stable dominant frequency between 0.6 ~ 1.7Hz. Because of the large scale vortex, the vibration has good similarity and synchronicity. The vibration strength increases stably with the increase of discharge amount, while the dominant frequency decreases slowly. When the discharge is more than 1500m3/s, the dominant frequency tends to decrease at low speed and become stable eventually.