Modeling and Simulation of the Consolidation Behaviour of Cemented Paste Backfill

In underground mining operations, the mined-out spaces (called stopes) need to be backfilled to maintain the stability of surrounding rock mass and increase the ore recovery. Cemented paste backfill (CPB), a mixture of water, binder, and tailings, has been intensively utilized in underground mining operations to fill the stopes. After preparation, the fresh CPB is transported into stopes via gravity and/or pumping. The CPB in stopes is subjected to thermal, hydraulic, mechanical and chemical loads. As a result, the consolidation behavior of CPB is dominated by complex multiphysics processes that occur within the CPB. However, the conventional consolidation theory mainly focuses on the coupled mechanical and hydraulic processes. Therefore, it is necessary to develop a multiphysics model for the assessment and prediction of the consolidation behavior of CPB. In the study, a 3D coupled multiphysics model is proposed and implemented into Comsol Multiphysics. The predictive capability of the proposed model is validated against experimental data collected from well-controlled laboratory experiments. Three different coupled modules including geomechanics, subsurface flow and heat transfer modules are adopted. The prediction results show a good agreement with the measured data, which verifies the good prediction capability of the developed model.