The Study On The Seismic Performance Of Inserted Junction In Composite Dam

Composite dam refers to the hydraulic complex, which adopts concrete dam in the middle to overflow and earth-rock dam to retain water on the both sides. This type of dam can make full use of terrain conditions, and it has the advantages of low cost. However, while the stiffness of concrete is very large, the stiffness of earth and rock material is relatively small. The difference of stiffness will lead to non-uniform distribution of deformation and stress on the bonding surface. The contact surface of concrete dam and rock-fill dam shows different vibration behavior in the process of seismic. Therefore, the relative settlement and cracks may occur at the inserted junction. So, the inserted junction is the weak point of the dam and should be disposed properly.The Guanyinyan hydropower station was built in the middle reaches of the Yangtze river, in Yunnan province. The station adopts the composite dam as water retaining structure. The connection of the concrete dam and rock-fill dam are connected by the inserted junction, which is71m. The project is in high seismic intensity region. Under earthquake load, the dislocation displacement and tension cracks will appears at the inserted junction. Obviously, it is a weak part of dam related to the security global engineering. Based on this project, the permanent deformation analysis has been made on three kinds of inserted junction schemes. The main contents are as follows:(1) The article introduced the experimental process, the constitutive model and numerical simulation of the contact surface. It also briefly introduced the interface test at home and abroad, analyzed the characteristics of the common contact element types, and then summarized the constitutive models that were commonly used.(2) A three dimensional finite element model of Guanyinyan hydropower station was established. The contact surface apply the Goodman element, with thickness. The constitutive of contact element considered the influence of super residual stress and embedded displacement. The permanent deformation program was compiled.(3) The finite element analyses have been made to the rectangular junction, torsion junction and curved junction schemes. The results show that:from post-earthquake normal displacement of the interface, curved junction scheme was big, rectangular junction scheme took second place, torsion junction scheme was relatively small; from post-earthquake tangential of the interface, curved junction scheme was big, torsion junction scheme took second place, rectangular junction scheme was relatively small.