Numerical Simulation Of Failure Of Armour Blocks Of Rubble Mound Breakwater Based On FEMDEM

The rubble mound breakwater is the protective structure widely used in port and coastal engineering, and artificial armor blocks breakwater is one of the important section types. Armor blocks are concrete quasi-brittle material. During prefabrication, their joints are sometimes a little weak, and external loads may not only result in resonance, roll, collapse, collision and so on, but also lead to tensile stress and crushing. At the moment, the research on the stability and damage of breakwater at home and aboard is based on the physical model test. While the study on the fine simulation of armor block’s damage is rare, so it is of great significance to do research on the block deformation, stress variety and fracture failure under dynamic loads.This paper verifies the efficiency of the contact search method Munjiza-NBS. Munjiza-NBS is core part of FEMDEM(The Combined Finite-Discrete Element Method)which is used for the solid fracture. This paper verifies the Munjiza-NBS contact detection algorithm through the CPU and RAM by numerical examples. A block model library and slope is established by visual computer graphics technology and Delaunay triangulation’s mesh generator Easymesh, the visualization of the armor block’s failure process is realized by interface program, a Drawing Exchange File of AutoCAD.The article simulates the dynamic response with the model of four-point symmetrically supported concrete beam under impact. Meanwhile, the model’s stress distribution and stress value are verified by ABAQUS. The contrastive analysis is done about the concrete deflection curve. Concrete model is meshed by the method of independent nodal point. Based on the fictitious crack model which is integrated into FEMDEM, the cracks formation and fracture process is simulated. Graphical post-processing program processes the data results, which is analyzed and compared with concrete tensile damage.Based on above work, breakwater’s armor blocks interaction’s numerical examples are done, including quadrangle hollow block’s collision, arranged armor blocks stress peak value and concentration zone of stress on slope’s slip collision, collisional failure of two common armor block with given speed. The calculation results are analyzed and compared, and the paper sums up the general rules of block crack formation and development trend.The numerical simulation of collisional stress, crack formation and fracture process turns out that the tensile stress damage usually occurs in the border around the corner and crushing failure occurs at the vertex. The crack always comes into being in the corner of external boundary and then expands from the corner of the internal boundary to the corner of external boundary, what’s worse, even through breaking the block. FEM can effectively simulate structure deformation and stress, while DEM can effectively simulate objects’ contact force and following the nodal points’ movement. FEMDEM combines the FEM with DEM, so it is an effective method in the transition from continua to discontinua. The paper provides an effective method for the research on crack’s propagation, fracture failure of rubble mound breakwater’s armor blocks.