Soil-Structure Interface Behavior of Cemented-Paste Backfill Material Mixed With Mining Waste

Abstract

ABSTRACT:The use of mining wastes as a component of cemented paste backfill provides an environmentally acceptable method of waste disposal at a lesser cost as the method does not require tailing dams for storing the large volume of wastes. This study determines the applicability of cemented-paste backfill materials mixed with aggregate quarry wastes as ground support to concrete structures. Aggregate quarry waste with varying fine contents was used as a substitute for sand in cemented-paste backfill and the mixture was referred to as cemented-paste tailing backfill (CPTB). Its micro fabric structure was determined through SEM-EDX tests. Test results showed that CPTB with 20% and 40% fine contents has acceptable values of strength properties in terms of its unconfined compressive strength and interface friction angle. The unconfined compressive strength in relation to its curing period is in the range of 120 kPa to 150 kPa which can be described as having stiff consistency. The stress-strain interface behavior between CPTB and concrete structure was evaluated through a direct shear test using strain rates that simulate the rapid and slow rates of loading. In both conditions, the stress-strain behavior exhibits strain softening. The average interface friction angle is 38 o which can be associated with its dense condition. The modified hyperbolic model was applied to evaluate the soil-structure interface behavior of CPTB. Hyperbolic parameters were formulated to predict the interface shear stress -shear strain behavior of the CPTB when in contact with concretes structure at any value of shear strain and normal effective stress.

Temperature Effect on Mohr–Coulomb’s Effective Strength Parameters of Paste Backfill

“…The scarcity of minerals in the shallow ground level necessitates deeper underground level to be explored by the industry to stay profitable (Sheshpari 2015). Underground mining produces mined-out voids (stopes) that could cause underground instability and indirectly give impact to the ore recovery rate and safety issues (Rankine and Sivakugan 2007;Xuan et al, 2013;Adajar and Pabilona 2018). Concurrently, mining processing plants also generate a significant amount of waste rock and tailings.…”