Finite element-based stability charts for underground cavities in soft calcarenites

The stability of shallow, artificial underground cavities in soft rocks interacting with overlying structures and infrastructures represents a challenging problem to be faced. This paper discusses a methodology that can be useful for a preliminary stability assessment of underground cavities in soft calcarenites based upon the results of parametric two-dimensional (2D) and three-dimensional (3D) finite-element analyses of ideal underground cavities. The study aimed at exploring those relationships between the geometrical parameters of the cave system and the strength properties of the rock material to define charts that can be useful to evaluate the stability of the rock mass. Moreover, the influence of three-dimensionality was also accounted for based on 3D parametric analyses with variable cavity length and the comparison with the results of the corresponding 2D analyses.