Residual Strength Characteristics of CJPL Marble Under True Triaxial Compression

Excerpt

After excavation of underground caverns and tunnels, surrounding rocks suffer the development of the excavation damaged zone (EDZ), which still exhibits a certain bearing capacity (Hudson 1989; Hoek et al. 1995; Kaiser 2016). The studies of post-peak characteristics and residual strength play a crucial role in evaluating the bearing capacity (Cai et al. 2007a, b; Gao and Kang 2017). In recent decades, research on residual strength has made great progress and this has exerted a profound influence on the optimal design of supporting structures (Peng et al. 2017). However, the China Jinping Underground Laboratory Phase II (CJPL-II, with a burial depth of about 2400 m) is constructed under a state of three-dimensional (3D) high-geostress (Feng et al. 2018). The residual strength characteristics in this 3D stress state are not yet clear [e.g., the influence of intermediate principal stress (σ₂)], which deserved to be explored further. …