底流钢膜消力池底板上表面脉动压力试验

Experimental study on fluctuating pressure acting on the upper surface of the slab in a underflow stilling basin with a steel membrane

为确保消力池防护结构在水流冲击下的安全,探索一种新的钢膜消力池防护结构,即在消力池传统的不透水混凝土底板上部铺设一层均匀开孔的薄钢板。基于某底流消力池模型试验,研究了铺设均匀开孔钢膜对不透水底板上表面脉动压力分布规律的影响。试验结果表明:铺设均匀开孔的钢膜后,对于消力池前端旋滚区,脉动压力强度系数减小、概率密度函数基本满足正态分布,但幅值范围更加集中;纵向各点的相关性降低、空间积分尺度下降,涡旋保持性降低;脉动压力主频基本不变,但脉动能量集中的频带变窄。与透水底板比较,钢膜消力池防护结构可以有效减小作用在消力池前端底板上表面的脉动荷载,初步表明这种结构具有一定的可行性。

To ensure the safety of the protective structures of a stilling basin under high speed flow,stilling basin with a steel membrane is proposed as a new type of protective structure in which is a layer of thin homogeneous perforated steel plate is laid on the stilling basin slab. Based on hydraulic model test,the effect of the uniform perforated steel membrane on the distribution of the fluctuating pressure acting on the upper surface of the slab was studied. The results show that,when the uniform perforated steel membrane is laid,the fluctuating pressure intensity coefficient of the upper surface is reduced and the probability density function basically follows the normal distribution with more concentrated range of fluctuating pressure amplitude in the water rolling zone at the front of the stilling basin. The correlation and the spatial integral scale of the longitudinal points decrease,indicating that the vortex retention is reduced. The dominant frequency of the fluctuating pressure is basically the same,but the pressure fluctuation energy has a narrower band. Compared with the pervious slab,the protective structure of steel membrane can effectively reduce the fluctuating load acting on the upper surface of the slab in the front of the stilling basin,indicating that this new type of protective structure shows certain feasibility.