CAJ | 학술논문

为了模拟岩体中裂纹的萌生、扩展，Munjiza提出了有限元法/离散元法(FEM/DEM)耦合分析方法。因为裂纹是沿单元边界进行扩展的，亦即裂纹扩展具有网格依赖性，为获得较好的裂纹扩展形态，需要划分密集的初始网格。为解决上述难题，基于FEM/DEM耦合分析方法，提出了基于局部单元动态劈裂的FEM/DEM自适应分析方法，以克服裂纹扩展形态对网格的依赖性。该方法在最初建模时无需划分很密的初始网格，随着荷载的施加，对裂纹尖端附近的局部单元进行动态劈裂，为裂纹的后续扩展提供了更多可能的扩展方向，使得裂纹扩展不必沿着初始网格的单元边界扩展，即可以沿着单元内部进行扩展，裂纹扩展形态更为平滑，与实际情况更为接近。同时相对原FEM/DEM耦合分析方法一开始就划分很密的网格而言，新方法可以划分较为稀疏的初始网格，计算成本降低。最后，通过巴西劈裂算例与原FEM/DEM耦合分析方法对比，分析表明，新方法在一定程度上克服了裂纹扩展形态对初始网格的依赖性。
위료모의암체중렬문적맹생、확전，Munjiza제출료유한원법/리산원법(FEM/DEM)우합분석방법。인위렬문시연단원변계진행확전적，역즉렬문확전구유망격의뢰성，위획득교호적렬문확전형태，수요화분밀집적초시망격。위해결상술난제，기우FEM/DEM우합분석방법，제출료기우국부단원동태벽렬적FEM/DEM자괄응분석방법，이극복렬문확전형태대망격적의뢰성。해방법재최초건모시무수화분흔밀적초시망격，수착하재적시가，대렬문첨단부근적국부단원진행동태벽렬，위렬문적후속확전제공료경다가능적확전방향，사득렬문확전불필연착초시망격적단원변계확전，즉가이연착단원내부진행확전，렬문확전형태경위평활，여실제정황경위접근。동시상대원FEM/DEM우합분석방법일개시취화분흔밀적망격이언，신방법가이화분교위희소적초시망격，계산성본강저。최후，통과파서벽렬산례여원FEM/DEM우합분석방법대비，분석표명，신방법재일정정도상극복료렬문확전형태대초시망격적의뢰성。
In order to simulate initiation and propagation of rock crack, Munjiza proposed FEM/DEM coupling analysis method. Because the cracks extend along the cell boundary, i.e. the propagation of crack has mesh-dependency problems. For the purpose of a better crack propagation shape, dense initial mesh is needed. To solve the above problems, the FEM/DEM adaptive analysis methods of local unit dynamic splitting is proposed to overcome mesh-dependency problems of crack morphology based on FEM/DEM coupling analysis method. However, very fine elements will not be necessary in this procedure;and dynamic splitting can take place in the local elements containing crack tips with increasing loading, which provides more possible expansion direction for subsequent expansion of the crack. Cracks are not confined along edges of elements. Cracks can grow in more natural way, which can be extended inside the element and more smoother. While original FEM/DEM coupling method divides very dense mesh, the proposed method can divide initial mesh relatively sparsely;so the cost of calculation is low. Finally, the numerical example of Brazilian disc indicates that the proposed method overcomes the dependence of crack morphology on the initial grid.