Simulation Study Of Multiple Cracks Propagation In Concrete Based On Extended Finite Element Method

The concrete is made of a variety of composite materials and additives,and has been widely applied to roads,bridges and water conservancy fields,etc.At present,it is one of the most commonly used engineering materials.A large number of studies show that the failure of concrete structures is caused by crack propagation,which leads to fracture,and its causing accidents.Therefore,the study of crack propagation in concrete structures has become a hot topic for domestic and foreign scholars.The numerical method is a common tool for studying crack propagation.The extended finite element method is an effective numerical method developed in recent years to solve the problem of crack propagation.The application of this method to study the single crack in concrete materials has been relatively mature,but the study of ?-? mixed mode multiple cracks is relatively little.In this paper,the principle of multiple cracks extended finite element method was applied to numerically simulate the process of ?-? mixed mode multiple cracks in concrete members under the action of loading by combinning the virtual joint method and the cohesive crack model.The main contents and conclusions are as follows:(1)The cohesive crack model in concrete nonlinear fracture mechanics model and the crack propagation criteria of concrete were studied.The basic principles of the extended finite element method,including the unit decomposition method and the construction of the displacement function,were studied.Then the governing equations of multiple cracks extended finite element method were derived based on these.(2)The application of the extended finite element method and the cohesive crack modle on the finite element calculation software ABAQUS were proposed to numerically simulate concrete the four-point bending beam contained ?-? mixed mode multiple cracks.The process of multiple cracks propagation and the crack tip stress of the beam under the action of displacement loading were analyzed.The numerical simulation results were compared with corresponding results in the literature.The results show that the application of the extended finite element method can accurately simulate the whole process of ?-? mixed mode multiple cracks in concrete beam from loading to instability failure without having to remesh and reduce the computation.It has better convergence compared with the finite element method.(3)The extended finite element method was applied to simulate the multiple cracks propagation of the concrete gravity dam.The path of crack under multiple cracks interaction and the load-crack opening displacement of the main crack were analyzed.The results show that the path of multiple cracks propagation in concrete gravity dam is almost consistent with the results of the literature,and the load-crack opening displacement curve of the main crack has a little difference between them.