Symulacja pröby jednoosiowego sciskania pröbki ziarnistego materialu skalnego

Main features of a distinct element code PFC2D (Particle Flow Code in 2 Dimensions) have been briefly presented in the paper. The code was used to build a numerical discrete particle model of a certain medium-grained sandstone from Jastrzçbie Colliery. The model of the dimensions 42 mm × 84 mm (diameter x height ) consisted of about 4300 circular particles or balls with nearly uniform distribution of radii of between 0,25 mm and 0,75 mm (Fig. 3a). Prior to loading the sample had about 9600 bonds. Bulk density and porosity of the granular aggregate was 2700 kg/m3 and 5%, respectively. The normal and parallel bond strengths were about 1x10" N and normal (and shear) stiffnesses of parallel bond - about 1×10¹⁷ N/m. The computer simulation results were compared with the results of uniaxial compression tests. It has been found that PFC^2D can reproduce in numerical tests many of the qualitative features of the Jastrzçbie sandstone tested: almost the same was the ultimate strength (136 MPa and 134 MPa) and axial strain at peak stress (0,512% and 0,514%). Both real and numerical rock samples experienced shear faulting in the post-failure stage. Only one important quantitative discrepancy has been observed: the lateral (and volumetric) strain response was much greater in numerical than in laboratory experiments (Fig. 5). This phenomena has various intensity for different types of input data. Further work is required to better understand what the factors which govern the dilatant behaviour of PFC models of the clastic rock materials arc.