Experimental study on energy dissipation of layered backfill under impact load

Abstract

• The dynamic characteristics of layered cemented tailings backfill(LCTB) were studied by SHPB test system. • The failure of LCTB mainly occurs at the delamination of the specimen. • The reflected and absorbed energy of specimens gradually increases and the transmitted energy gradually decreases as the number of layers increases. • The specific energy absorption value (J EA ) and dissipation rate were significantly positively correlated with the number of layers. The failure of the cemented tailing backfill (CTB) under the impact load is mainly related to the absorption and dissipation of energy; in order to obtain the corresponding dynamic characteristics and energy evolution law, The diameter is 50 mm split Hopkinson pressure bar (SHPB) test system was conducted to investigate the influence of different layers, cement tailing ratios (CTR) and impact rates on the failure mode, dynamic stress–strain curve and energy evolution of the LCTB. The results show that: (1) with the increase in the number of layers, impact rate and CTR, the dynamic peak stress of the CTB gradually increases. When the impact rate is constant, the strength of the CTB gradually decreases with the increase of the number of layers. (2) With the increase in the number of layers, the reflection energy and absorption energy, specific energy absorption value (JEA) and dissipation rate of the CTB gradually increase while the transmission energy decreases gradually; with the increase of incident energy, the energy increment and dissipation rate of the CTB increase first and then decrease, suggesting that the energy absorption of the CTB will not change greatly when the incident energy increases to a certain extent. (3) Due to the filling layer, the basic particles forming the CTB will slip relatively at the layer while the stress wave acting on the layer, which intensifies the dynamic process at the layer and eventually induces the fracture of the CTB specimen along with the layer. With the increase in impact rate, the failure mode of the CTB without delamination mainly includes shear failure and axial splitting failure. Finally, this research can provide important theoretical support for the further study of underground LCTB.