PFC-FLAC coupling-based numerical simulation of triaxial test on soybean granular material

A discrete-continuous (PFC-FLAC) coupling method was used in this study to simulate laboratory triaxial tests with soybean granular material. The mesoscopic mechanical parameters of the soybean granular material were calibrated by comparing them with actual laboratory test results, and the validity of the modeling method was verified. Subsequently, the particle motion law and mechanical mechanism of the soybean granular materials were analyzed based on the particle displacement field, velocity field, and force chain network. The results showed that the coupled PFC-FLAC method could better describe the macroscopic stress-strain relationship, deformation damage characteristics, and shear strength mechanical indexes of soybean granular materials. With increasing confining pressure (50-200 kPa), the bulging deformation of the specimens changed from uniform to concentrated but uneven. The particle contact number and maximum particle contact stress increased by 19.3 and 48%, respectively. Additionally, variations of the macroscopic properties of the specimens with microscopic parameters were revealed. Under the same conditions, the change in the peak stress of the specimen was proportional to the interparticle friction coefficient. Moreover, the slope of the stress-strain curve increased gradually with an increase in the effective modulus.