三峡泄洪坝段纵缝对地震反应影响的研究

Influence of Longitudinal Joints on Seismic Response of Spillway Dam of the Three Gorges Project

泄洪坝段是三峡工程的重要建筑物之一,最大坝高181.0 m,以前的大坝抗震分析是按整体结构模型。现按实际情况设置施工纵缝,研究在地震作用下纵缝的接触状态以及泄洪坝段的响应。分别建立整体、有纵缝无间隙和有间隙3种模型进行地震响应分析比较,缝面按接触状态非线性问题处理,计算采用时间逐步积分法。研究结果表明:整体坝与有纵缝坝的地震动力响应存在着差异,有纵缝坝似3根叠梁,缝两端的两侧应力不连续,但三峡泄洪坝仍能保持与整体坝基本相同的功能。

The Three Gorges spillway dam section with a maximum dam height of 181.0 m,is one of the important constructions in the Three Gorges Project.The previous seismic investigations on the spillway dam in the past years did not take into account the longitudinal construction joints of the dam body.On the basis of the actual dam with longitudinal joints,the contrast state of the joints in the seismic response of the dam under earthquake has been carried out.The investigation included three different dam structure models： the dam without longitudinal joints,the dam with joints but without joint gap,and the dam with joints and with joint gap.The contact property of the gap was assumed to be nonlinear and a time step-by-step integral method was adopted.The results given in this paper indicates that the seismic responses of the spillway dam with or without joints are different.The dam with joints in performance seems like a three overlapping beam,in which the stress is discontinuous at two ends of the joint.However,the dam model with longitudinal joints still satisfies the seismic design requirements as the dam in its entirety.