预应力坝后背管结构设计与有限元分析

Structural Design and Finite Element Analysis of Prestressed Penstock Downstream of Dam

针对普通坝后背管在裂缝控制和耐久性等方面的弱点,提出预应力坝后背管这种新的结构形式。它是在普通背管中施加预压应力,使结构处于弹性工作状态下,其外包混凝土在正常荷载组合作用下不出现裂缝,或虽然超载后产生裂缝,但正常情况下裂缝仍处于闭合状态,因此结构的整体性和耐久性大大提高了。结合某水电站坝后背管的具体资料,从环形后张预应力作用机理出发,在普通坝后背管基础上对预应力背管进行结构设计和有限元分析校核。结果表明,预应力坝后背管结构是安全、耐久和经济的。

Aiming at the defect of crack control and durability of ordinary penstock downstream of concrete dam, a new structural form of steel lined prestressed concrete penstock is presented in this paper. It is to form prestressed pressure in ordinary penstock, so the penstock structure is in the elastic working state and the concrete encasing the penstock has no cracks under the combination of normal loading; even it has cracks under overloading, but the cracks are closed in normal conditiorL Thus, the integrity and the durability of the structure are improved greatly. Based on the data of the penstock downstream of a dam in a hydropower station, the structural design and FEM analysis of the prestressed concrete penstock are carried out from the mechanism of annulus reinforcement effect. The analysis shows that the prestressed concrete penstock is safe, durable and economical.