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重力坝深层滑动主要表现为沿缓倾角的软弱结构面形成滑移通道,滑移通道内应变积聚且应变梯度急剧不连续,是典型的应变局部化现象,采用经典连续介质理论进行数值模拟时存在病态的有限元网格依赖性。引入Cosserat连续体理论作为正则化机制,提出了基于Cosserat理论的Mohr-Coulomb弹塑性模型,考虑非关联的流动法则,在经典塑性理论框架下采用向后Euler隐式积分算法进行应力更新。采用ABAQUS的自定义单元接口(UEL)进行二次开发,进行了平面应变条件下单轴受压的数值验证。数值模拟结果表明,该模型能保证应变局部化问题的正定性。基于Cosserat理论的重力坝深层抗滑稳定分析结果表明,采用超载法进行重力坝渐进破坏过程模拟时,基于经典连续体理论的模拟结果有较大的网格依赖性,而且结果偏于安全,而采用Cosserat连续体理论的结果对网格密度不敏感。
The deep sliding of the gravity dam is mainly characterized by the formation of slip channels along weakly inclined plane of weak dip, the accumulation of strain in the slip channels and the sharp discontinuity of the strain gradient, which is a typical strain localization phenomenon. The classical continuum theory is used for numerical simulation Morbid Finite Element Grid Dependence. The Cosserat continuum theory is introduced as the regularization mechanism. The Mohr-Coulomb elastoplastic model based on Cosserat theory is proposed. The backward Euler implicit integration algorithm is used to update the stress under the classical plastic theory. The secondary development was carried out by using ABAQUS custom unit interface (UEL), and the numerical verification of uniaxial compression under plane strain was carried out. The numerical simulation results show that the model can guarantee the positive definiteness of the strain localization problem. The results of deep anti-slide stability analysis of gravity dam based on Cosserat theory show that the simulation results based on classical continuum theory have a large grid dependence when the overloading method is used to simulate progressive failure of gravity dam, and the results are biased towards safety. The results using Cosserat continuum theory are not sensitive to the grid density.