Modification of rock stress factor in the stability graph method: a case study at the Alhada Lead-Zinc Mine in Inner Mongolia, China

The stability graph is an empirical approach to predicting stope performance based on the geometric dimensions of stopes and the geotechnical conditions of the surrounding rock mass. Stability graph is commonly used to design and estimate the stability of open-stope mines and underground openings. Most engineers calculate the rock stress factor by the stability graph method considering the maximum principal stress at the center of the critical face and the uniaxial compressive strength of the intact rock, whereas the spatial multidimensional stress state, compressive strength of the rock mass, and tensile strength of the rock mass are not taken into account. In this study, the maximum and the minimum principal stresses dominating the rock stress factor are introduced into the stability graph. The rock stress factor ( A ) is modified by the Mohr-Coulomb criterion with tensile cutoff . The modified stability graph method was validated by adopting Cavity Monitoring System (CMS) laser technology, and it was then successfully applied in a case study at the Alhada Lead-Zinc Mine in Inner Mongolia. Compared with Mitri’s method, the proposed stability graph expands the scope of the narrow vein stope design dimensions. The modified rock stress factor in the stability graph provides a technical basis for the subsequent recovery of residual orebodies.