Evolutive fracture behavior of cemented paste backfill

Abstract

Underground mining is a key global industry that produces many of the mineral resources needed by several sectors of the economy. However, underground mining extracts large volumes of material from below the ground, which not only creates substantial subsurface voids, bult also produces high volumes of solid waste. Consequently, the potentially catastrophic failure of underground openings and environmental issues such as acid mine drainage has attracted increasing attention. To ensure the safety of mining workers and equipment and sustainably reuse the mine waste materials, cemented paste backfill (CPB, an engineered mixture of tailings, hydraulic binder, and water) technology has been widely adopted in underground mines around the world. Since CPB materials are used as the key ground support measure, the mechanical behaviors and properties play crucial roles in the safe design of CPB under complex field loading conditions. As a type of cementitious materials, the failure process is governed by the development of tensile and shear crack in CPB matrix under various loading conditions. Meanwhile, due to the progression of cement hydration, CPB materials also demonstrate curing time-dependent evolution of mechanical behaviors and properties. Moreover, a considerable amount of water is utilized to prepare the CPB paste and thus affects the particle interaction and cement hydration. Therefore, it is of theoretical and practical importance to investigate the effect of mix recipe and hydraulic factors on the evolutive fracture behavior and properties of CPB under mode-I (i.e., tensile stress), mode-II (in-plane shear stress), and mode-III (out-of-plane shear stress) loading conditions at different curing times. However, previous studies focus mainly on the conventional geomechanical behaviors, including compressive, tensile, and shear behaviors, of CPB. [...]