水电站进水口漂浮式拦污排张力计算

Calculation method for tensile force of drift trash barrier installed at the inlet of hydropower station

水电站进水口漂浮式拦污排由若干浮箱链接成索状,可简化为柔系平面结构。将水流、风和波浪对拦污排浮箱的作用转化为链节点作用力,然后根据虚功原理导出描述拦污排平衡状态的非线性方程组,并采用迭代方法求得漂浮式拦污排轴线张拉形状和张力数值解。洪江水电站工程实例计算结果表明:拦污排形态和轴向张力分布规律受水流单独或与风、波浪组合作用的影响非常明显,不同运行工况呈现不同的形态,且张力一般呈非均匀分布,岸边支墩反力值大于坝前支墩反力值,张拉形态和张力分布与悬链线理论计算结果差别较大。尤其在不发电泄洪运行工况下,进水口水域主流方向变化显著、流速增大,拦污排将出现非稳定性态,可能产生流体诱发大幅度摆动。

The drift barrier installed at the intake of hydropower station for preventing the trash is a flexible system formed by linking floating tanks. The system can be simplified as a cable with forces acting at the linking points. The forces include the drags of flow and wind as well as the wave action. Nonlinear equations describing the equilibrium state of the system are derived based on the virtual work principle and the numerical solution of the shape and tension of the cable are obtained by iteration calculation. The calculation result of an example shows that the tension of the system is significantly affected by flow drag or the combination of the flow drag with wind and wave actions. The shape and tension of the flexible system varies with the operation conditions of the power station. The calculation result is significantly different from that according to catenary's theory.