Determination of Geometrical and Structural Representative Volume Elements at the Baihetan Dam Site

A case study at the Baihetan dam site was undertaken to obtain a representative volume element (RVE) size. Two-dimensional fracture information in an exploration tunnel was used to generate a large three-dimensional fracture network. By dividing the entire modeled rock mass into cubes, the volumetric fracture density (P₃₂) value of each cube was determined. The size effect can be determined by changing the cube size. The RVE was determined using P₃₂ calculation and statistical tests, including Kolmogorov-Smirnov (KS) and Wilcoxon rank-sum tests. The P₃₂ value depends on the geometrical parameters of fracture density and size; in this study, this value is called the geometrical RVE. P₃₂ is dependent on fracture density and size, and cannot appropriately reflect certain data such as fracture dip or dip angle. Therefore, we propose a structural RVE (SRVE) considering fracture dip direction, dip angle, density, and size, which together constitute the available information about the fracture network. Therefore, the SRVE is more applicable for use in solving geological problems than the RVE. In this analysis, the KS and Wilcoxon rank-sum tests were used to determine the SRVE size.