Abstract
Cemented backfill is a mixture comprising dewatered tailings, a cementitious binder, and treated mine water. It is used to fill excavated cavities created during underground mining operations. Once placed in excavated cavities, the backfill material undergoes thermal (T), hydraulic (H), and mechanical (M, including self-weight and stress from surrounding rock mass) processes, along with THM coupling effects. Consequently, the mechanical properties of in-situ cemented paste backfill (CPB) can vary significantly from laboratory results. Relying solely on laboratory data for backfill design may result in underestimated or overestimated strength, potentially increasing backfill costs and compromising safety and stability in mining stopes. This study introduces a Cemented Backfill Twin Curing Apparatus (TCA) integrated with the THM effect to assess how the in-situ Thermal-Hydraulic-Mechanical environment affects the mechanical properties of backfill material. Subsequently, the TCA was employed to create paired CPB samples, which were subjected to in-situ curing, followed by a series of macro-micro experiments aimed at uncovering the interrelationships between cemented backfill strength and multifactor coupling effects. These findings have the potential to enhance the design of cost-effective, stable, durable, and environmentally friendly backfill structures.