Analysis of sensitivity factors on CJB mechanical behavior from specimen scale to engineering scale

Abstract

The mechanical behaviors of columnar jointed basalts (CJBs) are affected by various sensitivity factors and show significant cross-scale differences. Employing the representative models ranging from individual CJB specimens to tunnels, the sensitivity factors including joint mechanical characteristics, mesoscopic rock constitutive relations, and model boundaries are meticulously considered. Combined with digital image correlation, these models are rigorously tested against the meso-damage mechanics, statistical strength theory, and continuum mechanics. Subsequently, a comprehensive examination ensues, delving into the spectrum of influencing factors, fracture mechanisms, and sensitivity analyses of CJBs. Notably, it emerges that the mechanical anisotropy of CJB specimens is most susceptible to boundary condition, while joint mechanical property is more sensitive than mesoscopic rock constitutive relation. Furthermore, the specimen height-width ratio exhibits relative insensitivity, whereas the excavation stage is relatively sensitive for CJB tunnel. The proportional distance of subsidiary joint set manifests a lesser impact compared to the other parameters. Besides, from specimen scale to tunnel scale, the sensitive factor rankings on the mechanical behavior of related models are summarized. These achievements not only enhance our understanding of cross-scale CJB mechanics but also provide crucial knowledge for experimental setup, engineering design, and lifecycle management of CJB-involved projects.