Mechanical behaviour and failure characteristics of cemented paste backfill under lateral unloading condition

A key issue associated with mine backfill design is the determination of mechanical behaviour and failure characteristics of the cemented paste backfill (CPB), especially for CBP under lateral unloading conditions caused by excavation of adjacent stopes. In this research, a series of lateral unloading tests with RFPA3D were conducted to investigate the relationships among the cement-tailings ratio (1:4 and 1:8), lateral unloading stress (0 MPa, 0.2 MPa, 0.4 MPa, 0.6 MPa, 0.8 MPa and 1.0 MPa), mechanical behaviour, failure modes and acoustic emissions (AE) characteristics. Similar mechanical behaviour of all the CPB specimens was obtained. With different cement-tailings ratios and preloading stress values, the ultimate failure modes of CPB specimens show different forms. Additionally, increasing the preloading stress value caused a rising of AE counts. The results of this study can provide a significant reference for the backfill design and study of underground mining.