Application of kinetic damping in dynamic material point method for static problems

Material point method (MPM) is widely used in geotechnical engineering, owing to its powerful capability of modelling large deformation problems. But the static equilibrium problems involving very large deformation and material non-linearity can be difficult to solve using the quasi-static MPM, because of numerical difficulties with convergence in iterative procedure. An alternative method is the dynamic relaxation (DR) method, which converts the static problem to a dynamic one by considering the virtual masses and artificial damping. This paper presents a method to solve static problems using dynamic MPM with DR technique. An energy ratio and a force ratio are defined to recognize the static equilibrium state from dynamic process first. Then the kinetic damping as an DR technique is introduced into the dynamic MPM for the first time. Finally, two numerical examples are presented to illustrate the convenience and efficiency of the kinetic damping in dynamic MPM for static problems

Application of kinetic damping in dynamic material point method for static problems

Material point method (MPM) is widely used in geotechnical engineering, owing to its powerful capability of modelling large deformation problems. But the static equilibrium problems involving very large deformation and material non-linearity can be difficult to solve using the quasi-static MPM, because of numerical difficulties with convergence in iterative procedure. An alternative method is the dynamic relaxation (DR) method, which converts the static problem to a dynamic one by considering the virtual masses and artificial damping. This paper presents a method to solve static problems using dynamic MPM with DR technique. An energy ratio and a force ratio are defined to recognize the static equilibrium state from dynamic process first. Then the kinetic damping as an DR technique is introduced into the dynamic MPM for the first time. Finally, two numerical examples are presented to illustrate the convenience and efficiency of the kinetic damping in dynamic MPM for static problems

Discrete Element Modeling of the Effect of Particle Shape on Creep Behavior of Rockfills

Rockfills are widely used in civil engineering, such as dams, railways, and airport foundations in mountain areas. A significant long-term post-construction settlement may affect the serviceability or even the safety of rockfill infrastructures. The creep behavior of rockfills is influenced by a number of factors, such as particle size, strength and shape, water condition and stress level. However, the effect of particle shape on rockfill creep still remains poorly understood, which deserves a careful investigation. Particle-based discrete element method (DEM) was used to simulate the creep behavior of rockfills under different boundary conditions. Both angular and rounded particles were considered in this numerical study, in order to investigate the influence of particle shape. The preliminary results showed that angular particles experience more breakages and larger creep strains under one-dimensional compression than rounded particles. On the contrary, larger creep strains were observed in he rounded specimens in the direct shear test. The mechanism responsible for this difference is that the possibility of the existence of key particle in rounded particles is higher than that in angular particles. The above simulations demonstrate that the influence of particle shape on the creep behavior of rockfills can be simulated by DEM properly. The method of DEM simulation may facilitate our understanding of deformation properties of rockfill materials