Numerical and Experimental Analysis of Water and Rock Pressure Effects on Mine Isolation Barriers—Case Study of a Mining Disaster Investigation

The structural integrity of isolation dams in deep coal mines is critical to preventing underground disasters, particularly those involving water and waste-mixture inrushes. This study presents a forensic root-cause analysis, using reverse-engineering techniques, of a specific isolation-dam rupture to determine the failure mechanism under complex stress conditions and limited data availability. A hybrid investigative methodology was employed, combining sequential post-failure documentation analysis with physical-scale modelling and numerical simulations to reconstruct a deadly disaster for criminal investigation purposes. A 1:5 scale physical model of the excavation and dam was constructed using original construction materials to test the structure’s resistance to hydrostatic pressure. The experimental results demonstrated that the dam maintained integrity under static hydraulic loads representative of real-world conditions, with only minor seepage (“sweating”) and no structural failure over a 7-day monitoring period. To investigate external geomechanical factors, Finite Element Method (FEM) simulations were conducted using ANSYS software. The numerical analysis evaluated the effects of rock mass pressure and convergence on the dam’s stability. The results indicate that while the dam was designed to withstand significant hydraulic head, the failure was precipitated by excessive rock mass pressure at a depth of around 600 m, which induced critical stress concentrations exceeding the masonry’s load-bearing capacity. This study confirms that the dynamic rupture was driven by unforeseen geomechanical forces rather than hydrostatic overload alone, highlighting the necessity of considering rock mass–structure interaction in the safety assessment of underground isolation barriers. This approach enables mutual verification of the results obtained and reduces the ambiguity of interpretation that often accompanies the analysis of accident events in underground mining. It also confirms the application of tested methodology for mining disaster reconstruction as proof at the stage of investigation and in the Court.