Amirkabir University of TechnologyAmirkabir Journal of Civil Engineering2588-297X52320200521Simulation of Critical State Behavior of Granular Soils with Polygonal Particles Using
Discrete Element Method (DEM)Simulation of Critical State Behavior of Granular Soils with Polygonal Particles Using
Discrete Element Method (DEM)711732310910.22060/ceej.2018.14853.5760FAMasoudKhabazianFaculty of Engineering, Ferdowsi University of MashhadEhsanSeyedi HosseininiaCivil Eng. Department, Faculty of engineering, Ferdowsi University of Mashhad0000000298108698Journal Article20180818In this study, the numerical Discrete Element Method (DEM) was applied for simulating both drained and undrained behavior of granular materials with two-dimensional polygonal particles in order to find a critical state line. For undrained behavior simulation, two methods including constant volume and cylinder methods were utilized. In the constant volume method, it was assumed that the volume of the soil remains constant during the loading due to the incompressibility of water. In the cylinder method, however, a pipe was considered among adjacent pores that provide the water transformation between them. In other words, the transmission of water among the voids can be taken into account. An undrained simulation was performed for sandy samples at the confining pressure of 200 kPa by both methods. Simulations showed that the results obtained by the cylinder method have good conformity with those of the constant volume method. A parametric study on the water compressibility was done. As the water becomes less compressible, i.e., stiffer, the stress-strain paths of both methods become closer. Also, the effect of confining pressure on the drained and undrained behavior by constant volume and cylinder methods was investigated. The results of the simulations showed that by increasing the confining pressure, the deviatoric stress and the contraction tendency increase in drained and undrained simulations. To achieve a critical state in the soil samples, the simulations were performed with a large strain level where both deviatoric stress and void ratio become constant. Then the critical state line locus, as well as its parameters, are determined. The results show that the critical state line locus does not depend on the stress path. Furthermore, the simulation method for the undrained condition has very little impact on the critical state line locus.In this study, the numerical Discrete Element Method (DEM) was applied for simulating both drained and undrained behavior of granular materials with two-dimensional polygonal particles in order to find a critical state line. For undrained behavior simulation, two methods including constant volume and cylinder methods were utilized. In the constant volume method, it was assumed that the volume of the soil remains constant during the loading due to the incompressibility of water. In the cylinder method, however, a pipe was considered among adjacent pores that provide the water transformation between them. In other words, the transmission of water among the voids can be taken into account. An undrained simulation was performed for sandy samples at the confining pressure of 200 kPa by both methods. Simulations showed that the results obtained by the cylinder method have good conformity with those of the constant volume method. A parametric study on the water compressibility was done. As the water becomes less compressible, i.e., stiffer, the stress-strain paths of both methods become closer. Also, the effect of confining pressure on the drained and undrained behavior by constant volume and cylinder methods was investigated. The results of the simulations showed that by increasing the confining pressure, the deviatoric stress and the contraction tendency increase in drained and undrained simulations. To achieve a critical state in the soil samples, the simulations were performed with a large strain level where both deviatoric stress and void ratio become constant. Then the critical state line locus, as well as its parameters, are determined. The results show that the critical state line locus does not depend on the stress path. Furthermore, the simulation method for the undrained condition has very little impact on the critical state line locus.https://ceej.aut.ac.ir/article_3109_969c271d25cbb4d72811f8b285455481.pdf