Analytical solution to non-isothermal pore-pressure evolution in hydrating minefill

Abstract

Anomalous rises in minefill pressure during deposition shutdown have been increasingly reported in recent field investigations, raising growing concerns over contemporary underground tailings disposal. While constrained backfill expansion during hydration-heat release has been invoked to rationalize such perplexing observations, a benchmark for understanding the complex minefill response to thermal loading is still lacking. A novel analytical procedure is thus proposed in this study to characterize the non-isothermal evolution of pore pressure in cemented backfill hydrating in undrained adiabatic settings. By constructing a suitable variable system and selecting a proper auxiliary parameter for calculation, the proposed strategy based on canonical thermo-poroelasticity could enable straightforward implementation and has shown excellent compliance with computational and experimental results. The analytical results suggest that because higher temperature could stimulate cement hydration while enhancing simultaneously fluid expansivity, the pore pressure would decline initially with the rising curing temperature and then revert to increase after a critical threshold. Moreover, our investigation has shown that increasing binder usage is not always conducive to pore-pressure dissipation, as the payoff can be also hinged strongly upon the initial thermal condition. These findings could better elucidate the intriguing control of coupled multiphysics processes on backfill behaviour, and can also serve benchmarking purposes for sophisticated computational procedures.