基于Cosserat理论的重力坝深层抗滑稳定分析  

Deep anti-sliding stability analysis of gravity dam based on Cosserat continuum theory

作　　者：马刚[1,2] 常晓林[1,2] 周伟[1,2] 周创兵[1,2] 

机构地区：[1]武汉大学水资源与水电工程科学国家重点实验室,武汉430072 [2]武汉大学水工岩石力学教育部重点实验室,武汉430072

出　　处：《岩土力学》2012年第5期1505-1512,共8页Rock and Soil Mechanics

基　　金：国家自然科学基金(No.51079113;No.51179139);国家自然科学杰出青年基金(No.50725931)

摘　　要：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 slide of gravity dam is mainly reflected in the appearance of sliding channel along the slow-inclination of weak structure plane.The strain accumulates in sliding channel with very sharp discontinuous strain gradient is a typical strain localization phenomenon.The classic continuum theory suffers from the pathological mesh-dependence in strain localization problem of strain softening material in failure analysis.In this contribution,the governing field equations are regularized by adding rotational degrees-of-freedom to the conventional translational degrees-of-freedom and an elastoplastic Mohr-Coulomb model is presented based on the Cosserat continuum theory,in addition,non-associated flow rule is adopted.In the framework of classic plastic theory,the backward Euler algorithm is used to update plastic stress.A uniaxial compression is performed;the numerical results show that the load-displacement curves are uniformly converged upon different mesh sizes and mesh-independence solutions can be obtained.Finally,the overloading method is adopted in the gradually destruction process simulation analysis.The simulation results show that the classical continuum theory has salient mesh-dependence and are inclined to risk;otherwise the Cosserat theory is more reasonable.

关 键 词：重力坝 抗滑稳定 应变局部化 COSSERAT理论 

分 类 号：TU457[建筑科学—岩土工程]