摘要
Abstract
The water hammer velocity is a key parameter for calculating pipeline water hammer pressure,and the accurate calculation of water hammer velocity in composite pipes is an urgent scientific problem that needs to be solved.According to the original definition of water hammer wave velocity,the functional relationship between water hammer wave velocity and circumferential strain rate on the inner wall of the pipeline,as well as the functional rela-tionship between circumferential strain rate and circumferential,radial,and axial stress change rates,have been established.On this basis,considering the mutual influence of strain rate,interfacial pressure,pipe mechanical parameters,and structural dimensions of composite pipes,a general formula for accurately calculating the water hammer wave velocity in composite pipes is proposed.Then,by analyzing the factors that affect the general formula,the approximate formulas for the water hammer wave velocity of thin-walled composite pipes are derived,including thin-walled lining tunnels and underground buried pipes.The problems and applicable conditions of the traditional formula for water hammer wave velocity in composite pipes are analyzed.Finally,it is demonstrated through numeri-cal examples that:(1)for composite pipelines with thick wall layers,the general formula for accurately calculating water hammer velocity should be used;(2)The traditional formulas for water hammer velocity in composite pipelines are only applicable to thin-walled composite pipes;(3)The water hammer velocity of PCCP pipes is between 945 and 1184 m/s;(4)When the pipeline is laid underground,the wave velocity in the pipeline slightly increases due to the influence of backfill soil,and the impact is relatively small.关键词
复合管道/水击波速/应变率/厚壁管道/薄壁管道/隧洞Key words
composite pipe/water hammer wave velocity/strain rate/thick-wall pipe/thin-wall pipe/tunnel分类
建筑与水利
