Study on the Dynamic Response Characteristics and the Damage Constitutive Model of Magnetite Based on the Energy Dissipation Method

In underground metal mining operations, pillars are often subjected to dynamic loads induced by blasting. To investigate the response characteristics of pillar rock mass under dynamic loading conditions and to propose a damage constitutive model based on energy dissipation to describe the mechanical behavior of magnetite, dynamic triaxial tests were first conducted on magnetite, and its energy evolution characteristics were analyzed. Subsequently, a damage variable based on energy dissipation was introduced, and a modification factor was proposed based on energy evolution parameters, thereby developing a new damage constitutive model. Finally, the fitting results of the proposed model were compared with those of the conventional damage constitutive model based on the Weibull distribution and with the experimental data. The results indicate that the energy evolution characteristics of magnetite during the loading process are closely related to the loading method, the loading process, and the development of damage. Energy evolution indicators, such as the proportion of elastic energy, can be used to quantitatively characterize and distinguish the elastoplastic evolution process of rock during loading. It is feasible to employ energy evolution indicators as modification factors for the damage constitutive model, and they possess clear physical significance, thus outperforming modification factors derived from statistical approaches. The proposed damage constitutive model accurately describes the response characteristics of rock under dynamic loading conditions and it performs particularly well in capturing the yielding and residual characteristics of the rock.