基于附加质量的混凝土重力坝地震仿真分析

Seismic simulation analysis of concrete gravity dam based on added mass method

  • 摘要: 为了研究混凝土重力坝在地震过程中的动态响应规律,采用ABAQUS三维附加质量法模拟桃林口大坝在迁安波作用下的动态响应,并研究了3个方向地震加速度在地震过程中的影响程度。计算发现:坝体虽未发生震损,但下游断面突变处最大拉应力达到2.56 MPa,临界于混凝土的动态抗拉强度值2.6 MPa,应引起注意,在设计中折坡处宜做成圆弧形,以减少应力集中;在地震过程中,坝体横河方向位移量达到了17.87 mm,极易造成相邻坝段发生碰撞破坏,工程中可进行横缝灌浆用以加固;同时计入3个方向的地震作用是对坝体最不利的计算方案,横河向地震加速度和垂直地震加速度在整个抗震分析中都有着重要影响,单纯考虑其中某一方向地震作用的做法严重失真。

     

    Abstract: In order to study the dynamic response of the concrete gravity dam during earthquake, the correctness of the ABAQUS 3D added mass subroutine was proved through the simulation of Koyna earthquake, and the dynamic responses of Taolinkou dam under the action of the Qian’an seismic waves were simulated. And studies of the influences of three directions of the earthquake acceleration during earthquake have been carried out. It is found from analysis results that the damage did not occur, but the maximum tensile stress of the downstream mutation reached 2.56 MPa, less than the critical value of the dynamic tensile strength of concrete 2.6 MPa slightly, to which more attention should be paid in the design. In the design, the slope is advised to make a circular arc shape in order to reduce the stress concentration. During the earthquake, the displacement in the vertical flow direction reached 17.87 mm, which is extremely easy to cause the adjacent dam to collide. So during the construction of works, it can be avoided by transverse joint grouting. Counting the earthquake actions of three directions at the same time is the most unfavorable for the dam body, and the acceleration of the vertical direction and the acceleration of vertical rivers direction all have important influences on the seismic analysis. And the practice of only considering the seismic action of a certain direction is seriously distorted. This seismic simulation analysis is expected to provide more insights into the seismic performance of the gravity dam and to optimize the seismic measures.

     

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