A Novel Method of Calibrating Micro-Scale Parameters of PFC Model and Experimental Validation

Abstract

As a powerful numerical analysis tool, PFC (Particle Flow Code) is widely applied to investigate the mechanical behavior of rock specimen or rock engineering under different stress states. To match the macroscopic properties of the PFC model with those of the rock, a set of micro-scale parameters of the model needs to be calibrated. Thus, this paper proposed an optimization method combining Box–Behnken experimental design and desirability function approach to quickly and accurately find the values of the micro-scale parameters. The sensitivity of the main micro-scale parameters (mean value of parallel-bond normal strength σc, ratio of particle normal to shear stiffness Ec, and Young’s modulus at each particle–particle contact kn/ks) and their interactions to the macroscopic responses (uniaxial compressive strength, Young’s modulus, and Poisson’s ratio) were thoroughly analyzed using response surface theory. After that, validation study was conducted on the calibrated model. The results manifest that the uniaxial compressive strength is extremely significantly affected by σc and kn/ks, the Young’s modulus is highly correlated with Ec and kn/ks, and the Poisson’s ratio is most significantly influenced by kn/ks. Additionally, the interaction of micro-scale parameters also has different impact upon the responses. Moreover, the simulated crack behavior around differently shaped openings in rock samples under uniaxial compression is found to be well agreeable with the experimental results, which verifies the reliability of the proposed method.

Numerical simulation study on the deformation and failure of a gently inclined bedding slope: a case study of the Jinhaihu landslide in Guizhou, China

“…The parallel bonding model is able to provide both forces and moments, in other words, shear, compressive and torsional resistance when mechanical behavior occurs between particles (Cundall and Strack 1979). When the normal or shear stress on the bond exceeds its normal or shear strength, fracture occurs as tensile or shear cracking, which is more suitable for simulating rock materials (Wu et al 2020). Therefore, the parallel bonding model is used in this paper.…”

Micro-parameter calibration of layered rock samples with a dual model in PFC3D based on a combined optimization method

“…Two contact models were used in the numerical model of layered rock samples. The contact among particles in intact rock assigned by the parallel bond model (PBM) had the characteristics that both force and moment can be transmitted [27,28], which can better reflect the mechanical properties of rock materials [29][30][31][32]. The contact among rock beddings adopted the smooth joint model ( SJM ), which was widely used in the modeling of layered rock mass [33][34][35].…”

Layout timing of mining roadways considering goaf and roof stability

“…The trial-and-error method was used to obtain the mesoscopic parameters of the block (Wu et al, 2020;Gao et al, 2021). The mesoscopic parameters of the block were obtained by calibrating the macroscopic mechanical parameters of the rock mass (Figure 8; Table 7), as listed in Table 8.…”