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水电站压力钢管或蜗壳外敷设的薄垫层,可以定量调节钢板和外围混凝土所分担的内水压力比例。目前,解析推导内压传递系数计算公式时尚未涉及垫层材料的非线性。本文基于多层圆筒理论和垫层的受力特点,尝试推导了考虑垫层材料的压缩非线性,以及垫层、钢管和混凝土之间存在间隙的内水压力传递系数λ的解析解。结果表明,垫层作为非线性材料,λ的大小受间隙、作用内水压力、垫层的厚度、残余应变及当前循环加载阶段的应力-应变关系的影响。算例表明,λ随垫层初始厚度变薄而增大,即垫层越薄,传递的内水压力越大。此外,λ随循环加-卸载次数的增加而逐渐减小,但当循环次数达到某一数值后,λ基本不再变化。
Hydropower station outside the pressure pipe or volute laying cushion layer, you can quantitatively adjust the steel plate and the external concrete to share the proportion of internal water pressure. At present, the non-linearity of the cushion material has not been involved in the analysis of the formula for calculating the internal pressure transfer coefficient. Based on the theory of multi-layer cylinder and the force characteristics of the cushion, this paper attempts to derive the analytic solution of the compressive nonlinearity of the cushion material and the internal water pressure transfer coefficient λ with the gap between the cushion, steel pipe and concrete. The results show that the cushion is a nonlinear material, and the size of λ is affected by the gap, the pressure of the acting inner water, the thickness of the cushion, the residual strain and the stress-strain relationship during the loading cycle. Numerical examples show that λ increases with the initial thickness of the cushion, ie, the thinner the cushion, the greater the pressure of the internal water transferred. In addition, λ decreases gradually with the increase of cyclic loading-unloading times, but λ basically does not change when the number of cycles reaches a certain value.