Integration of homogeneous structural region identification and rock mass quality classification

Abstract

In rock engineering projects, professionals assess the overall rock mass qualities using a sole value. However, the true qualities of partial rock masses are incompatible with such a value. To address this problem, the idea of regionally classifying rock mass qualities is proposed and the associated procedure presented. To achieve this goal, the probabilistic and deterministic joints within the study area were determined, and a three-dimensional joint network model was created. Then, the three-dimensional joint network model was discretized into interlocking subdomains, and the modified blockiness index (MBi) was used to finely identify the homogeneous structural regions, together with the k-means algorithm and the sum of squared errors (SSE). A synthetic model comprising homogeneous structural regions was developed and validated with respect to the extracted cross-sections. Next, an improved rock mass rating system (RMRmbi) was introduced, and the viability of RMRmbi was supported through a significant amount of theoretical cases and several real cases. Finally, visualization of regional RMRmbi classification results was performed. Results show that: (i) the homogeneous structural regions are finely demarcated in three dimensions, and (ii) the proposed idea can overcome the problem of rock mass quality classification using the conventional approach often leading to ‘overgeneralization’.

Accurate Identification of Broken Rock Mass Structure and Its Application in Stability Analysis of Underground Caverns Surrounding Rock

“…If the ratio is less than the threshold value ([v/v 0 ] = 5%) of the ratio derived from the typical measurement data of several sections that may be destabilized and indeed transformed into a stable state, the section is expected to stabilize the surrounding rock. Deformation rate ratio criterion as formula (5).…”

“…Shan Dong et al [4] proposed a classification method for fractured rock masses to classify rock masses based on their structural characteristics and degree of fragmentation. Qingfa Chenet et al [5] created a three-dimensional joint network model used to finely identify the homogeneous structural regions, with the aim to overcome the problem of rock mass quality classification when using the conventional approach, which often leads to 'overgeneralization'. In addition, many scholars have achieved excellent results in rock mass classification, rock fragmentation analysis, and the stability of discontinuous rock masses [6][7][8][9][10][11][12][13][14][15][16][17][18][19].…”