Calculation method of stress and stability of new old interface of heightening gravity dam

• 1、China Institute of Water Resources and Hydropower Research

Abstract：The problem of load separation of new and old concrete dam body exists in the heightening of back wall gravity dam. The old dam bears the dead weight of the old dam and the water pressure load of heightening the limited water level. The new dam bears the dead weight of the new dam and the increment of the water pressure load after heightening. The proportion of the load sharing is related to the condition of the interface. When the interface of the new and old concrete is completely bonded, the load sharing equation of the new and old dam can be solved by the method of mCalculation method of stress and stability of new old interface of heightening gravity damaterial mechanics. When the part of the bonding is carried out by the method specified in the code, it has been Hard to achieve. The finite element method can solve complex problems, but the mesh dependence of the stress results makes it difficult to match the control standard. In this paper, two methods of load sharing calculation under the condition of finite combination of new and old concrete are put forward: 1) structural mechanics method of variable cross-section member, that is, simplifying the new and old concrete block into variable cross-section member, connecting the force bar and shear bar between the dam bodies, simulating the steps of heightening and impoundment, and calculating the internal force of the member at the foundation surface of the new and old dam bodies; 2) equivalent stress method of finite element, using finite element method Considering the new and old joint surface, the mesh is divided, and the process of heightening and impoundment is simulated step by step. The stress at the foundation surface of the new and old dam body is obtained and equivalent to the internal force. Based on the direct reaction method proposed in this paper, the state of the joint surface can be simulated by adding and subtracting connecting bars or interface elements. These two functions have been added to saptis, a high performance simulation platform developed by the author. The dam stress and stability safety factor calculated by the two methods should meet the current scale requirements.

Keywords： back wall type extremely high gravity dam variable section bar equivalent stress reaction method