Stress and strain measurement for large physical models based on 3D-DIC

Physical modelling has long been used in the study of underground mining to, inter alia, understand strata movement, surface subsidence, and top coal caving. This paper explores the extended application of three-dimensional digital image correlation (3D-DIC) in the physical modelling of underground coal structures. By precise measurements of stress and strain around mining layouts subjected to varying loads, this study demonstrates the application of 3D-DIC to enhance the understanding of pillar and roadway behaviour under deep mining conditions. Measurements using LVDT and 3D-DIC were conducted during uniaxial compression tests on cylindrical synthetic samples to be able to compare the stress-strain relationships obtained by both methods. Large-scale benchmark tests of EPS (Expanded Polystyrene) foam were further performed to demonstrate the capability of 3D-DIC for localised stress and strain measurement of mining layouts within the physical models. The results demonstrate 3D-DIC as a reliable and precise technique for monitoring stress distribution within coal structures in complex geo-stress environments, providing deeper insights into the dynamic processes of pillar instability, rib bursts, roof movement, and floor heave.