Determination of a destressing scheme for the stiff main roof of an evaporite deposit using distinct element method

Abstract Solution mining in thick evaporites leaves large underground openings with no roof support. Stiff strata overlaying the production caverns pose a risk of sudden collapse as excessive loads lead to the sudden release of strain energy. This violent failure threatens the operational sustainability and safety. Destressing methods are commonly used to mitigate the risk by inducing fracture networks in the stiff layers. This study employs a discontinuum based numerical code to investigate the alternative destressing schemes on a typical solution mine layout. Regarded the operational practice and economy, the ribbon and borehole patterns were simulated with different configurations. Discrete Fracture Networks were used for implementation of the fractured region. While the ribbons were examined for spacings of 30 m, 60 m and 90 m, the boreholes were studied for straight and staggered patterns. A typical production with a single solution cavern was simulated on a staged manner and the stress-strain histories were monitored. Comparing the model results, the most viable destressing scheme was determined for solution mining. In advance, stress management was also investigated for destressing wherever multiple stiff layers exist.