一、绪言大多数溢洪道的基本用途是用来泄放最大洪水,以确保洪水通过水利工程时不危及大坝安全和大坝上下游不产生非容许的破坏.工程设计应尽量满足下列要求:(1)溢流堰具有足够的长度以通过设计流量;(2)溢洪道建筑物上容许的最小压力;(3)堰顶上容许的最大溢流水头;(4)水流流态的稳定性及确定的水力特性;(5)建筑物的稳定性;(6)为减轻下游冲刷而容许的出流条件;(7)地质、地貌及环境美化等方面.溢洪道的溢流能力可由其长度、形状、高度、闸门尺寸、行近段条件及闸墩或边墩的几何形式确定.在初步研究中,通常单宽流量较大的窄深式溢洪道将比中等单宽流量宽浅式溢洪道的造价为低.因而,在美国陆军工程兵团内,其容许的水头已由12.2m增大到18.3m,单宽流量由91.8m~2/s增大到183.6m~2/s.这种较高的设计水头可能使闸墩和边墩的侧收缩较大,导致了消能问题 I. INTRODUCTION The basic purpose of most spillways is to release the maximum flood to ensure that the floodwater does not endanger the dam when it passes through the water conservancy project and that non-perishable damage to the upper and lower reaches of the dam is not caused by the project design. 1) the weir has sufficient length to pass the design flow; (2) the minimum allowable pressure on the spillway structure; (3) the maximum allowable head of overflow at the top of the weir; (4) the stability and determination of the flow regime (5) Stability of buildings (6) Outflow conditions to reduce downstream scouring (7) Geology, geomorphology and landscaping etc. The overflow capacity of a spillway can be determined by its length, shape, Height, gate size, approaching conditions and geometry of sluice pier or side pier.In the preliminary study, narrow spillway with larger single-width flow rate is usually lower than that with medium-width single-width flow spillway Thus, within the US Army Corps of Engineers, the allowable head of water has been increased from 12.2 to 18.3 m and the single-wide flow rate has increased from 91.8 to 264 m 2 / s. This higher design The head may cause a large contraction of the pier and side pier, leading to energy dissipation problems