Finite Element Modelling of the Stability of Underground Mining Excavations at Old Mines – Slănic Salt Mine

The underground mining of the rock salt deposit from Slănic started over 350 years ago, in bell-shape room (Ocna din Deal and Ocna din Vale) and in large trapezoidal rooms (Carol, Mihai and Unirea mines), until 1970, generating a volume of underground excavations of over 5.3 million m³. Over time, these large excavations have lost their stability (collapse of the mines to the surface and various degrees of instability of the Carol and Mihai mines), keeping only the Unirea mine in operation for tourist purposes. This article is a synthesis of the analysis with 3D finite elements, in elasto-plasticity, of the state of stress and strain developed around the excavations and highlighting the factors that led to the loss of their stability, focusing on the Unirea mine.