Page 28 - 2025年第56卷第6期
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Calculation of water hammer velocity in composite pipelines
YANG Kailin
（State Key Laboratory of Simulation and Regulation of Water Cycle in River Basin，China Institute of Water
Resources and Hydropower Research，Beijing 100038，China）
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.
Keywords：composite pipe；water hammer wave velocity；strain rate；thick-wall pipe；thin-wall pipe；tunnel
（责任编辑：鲁 婧 韩 昆）
（上接第 704 页）
Effects of soil and water conservation of vegetation measures in the middle Yellow River
WENG Baisha，YANG Panpan，YAN Denghua，WANG Hao
（State Key Laboratory of Simulation and Regulation of Water Cycle in River Basin，China Institute of Water Resources
and Hydropower Research，Beijing 100038，China）
Abstract：Afforestation，grass planting，and natural restoration are typical soil and water conservation measures
（SWCMs）in the middle Yellow River. Analyzing these SWCMs’water and sediment regulating effects is of great sig⁃
nificance for understanding the mechanisms of runoff and the future situation of water and sediment in the middle
Yellow River. This article analyzed 1165 relevant literature and compiled 1089 datasets containing three indicators：
surface runoff modulus，sediment yield modulus，and average infiltration rate. It then conducted a quantitative analy⁃
sis of the water and sediment regulating effects of these SWCMs，as well as the influence of terrain slope and rainfall
intensity on these effects. The results indicate that the effects of soil and water conservation of afforestation and grass
planting increased with the increase of vegetation coverage，but decreased with the increase of terrain slope and rain⁃
fall intensity，especially when the rainfall intensity was more than 120 mm/h. The effect of soil water storage of natu⁃
ral restoration increased with the increase of restoration years，and the effects of water and sediment reduction were
relatively stable when the restoration years are between 30 and 60 years. The effective values of these SWCMs are pro⁃
posed to provide parameter support for numerical simulation. It is recommended that the vegetation cover of grass
planting should be controlled within 60% and afforestation should be controlled within 60%—70%.
Keywords：soil and water conservation measure；soil and water conservation；Meta-analysis；the middle Yellow
River
（责任编辑：王 婧）
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