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(1.武汉大学 水资源与水电工程科学国家重点实验室，湖北 武汉 430072;2.武汉大学 水工岩石力学教育部重点实验室, 湖北 武汉 430072;3.海绵城市建设水系统科学 湖北省重点实验室（武汉大学），湖北 武汉 430072)
Numerical Calculation Method of Stiffened Penstock’s Critical External Pressure
(1.State Key Lab. of Water Resources and Hydropower Eng. Sci., Wuhan Univ., Wuhan 430072, China;2.Key Lab. of Rock Mechanics in Hydraulic Structural Eng. of Ministry of Education, Wuhan Univ., Wuhan 430072, China;3.Hubei Key Lab. of Water System Sci. for Sponge City Construction (Wuhan Univ.), Wuhan 430072, China)

Abstract:Penstock is a common type of lining in water conservancy and hydropower projects, and its stability under external pressure is very important. In order to establish an accurate finite element method for calculating the critical external pressure of stiffened penstock, a reliable numerical model with multiple rings was proposed in the paper, and the results were compared with those calculated by the von Mises theoretical formula and the simplified formula used by design specification for steel penstocks. Considering the complex external environment, the influence of different constraint schemes of stiffening ring under the external pressure of penstock was comprehensively investigated. Based on the proposed numerical solution under particular constraint scheme, the effect of stiffening ring on the critical external pressure of penstock and its effective constraint length were studied. A new fast method for calculating the critical external pressure of stiffened penstock was developed based on the buckling critical external pressure formula of plain penstock. The results show that the eigenvalue buckling analysis in ABAQUS has high accuracy and is in good agreement with the results of the von Mises formula. However, the results of the simplified formula used in the specification differ from the von Mises formula to some extent with the change of the bending wave. For stiffened penstocks with different diameter-thickness ratios, the critical external pressure of the stiffened penstock increases with the increase of the constraints, and it decreases with the increase of the spacing and the ratio of the penstock. When the distance between the stiffening rings is greater than 20 m, no obvious fluctuation occurs. The fast calculation method for the critical external pressure of penstock presented in this paper can be applied to both plain penstock and stiffened penstock, which is accurate, simple and convenient, and can serve as an alternative method for the critical external pressure calculation in practical engineering.

SU Kai,WANG Boshi,ZHU Hongze,TAO Jun,XU Zhendong.Numerical Calculation Method of Stiffened Penstock’s Critical External Pressure[J].Advanced Engineering Sciences,2022,54(6):97-104.