用刚体弹簧元研究拱坝的地震破损过程

Study on seismic damage and rupture of arch dams by rigid-spring elements

在满足刚度、强度和荷载等效的基础上 ,本文采用三维刚体弹簧元模型模拟连续 -非连续介质系统 ,通过拱坝在自重和水压荷载作用下的位移场和应力场的计算 ,并且与有限元方法计算的结果对比 ,表明该法在模拟连续介质方面的精度在工程上可以接受。随后应用这一模型分析某拱坝的地震破损过程 ,计算结果表明 ,地震加速度峰值对拱坝整体性受损存在一临界值 ,对于研究的某拱坝 ,在选定的几何参数和物理参数条件下 ,当地震加速度峰值小于 0 4g时 ,坝体的整体性保持较好 ,地震引起的动力残余位移较小且呈线性变化 ;当地震加速度峰值大于 0 5g时 ,由于强震的往复作用 ,横缝以及水平施工缝的开裂造成拱坝中上部产生分离的混凝土块体 ,拱坝整体性受损较重。因此 。

Based on the principle of stiffness, strength and external load equivalence, a 3 D rigid body spring element model (RBSM) is presented in this paper to simulate the displacement and stress field of continuum and discontinuous media system. It is confirmed that the computed results of RBSM are agreeable with that obtained by the FEM when simulating continuum media. Detailed studies of nonlinear dynamic response and residual deformations of an arch dam are performed. Computed results demonstrate that the peak ground acceleration(PGA) has a critical value of 0 4g in the case of selected geometric parameters and physical parameters. When the PGA is under 0 4g, the integrity of the dam remains intact and the residual displacement caused by earthquake is small; when the PGA is larger than 0 5g, the repeated high seismic load cycles lead to the concrete blocks separated by cracks which are developed and accumulated along the transverse joints and the horizontal construction joints, the dam integrity is significantly affected in the upper central portion of the dam. For improving the earthquake safety of the dam, a seismic resistance belt with reinforcements along the crest of the dam is recommended.