Research on the Damage Evolution Law and Dynamic Damage Constitutive Model of High-Performance Equal-Sized-Aggregate Concrete Materials

AbstractHigh-performance equal-sized-aggregate (HPESA) concrete materials are mainly used as wall-off filling materials for underground engineering to meet the functional requirements of explosion prevention and shock absorption. However, the promotion and application of materials in underground engineering requires further understanding of its behavior in terms of damage evolution under impact load. A dynamic damage constitutive model able to describe the characteristics of material failure and deformation is thus required. According to the optimal energy-consumption ratio parameters of HPESA concrete materials, specimens that could meet the requirements of static pressure tests and split Hopkinson bar (SHPB) impact tests were prepared. The quasi-static testing parameters at a constant strain rate of 2.0×10−5 s−1 and the dynamic stress-strain curves at strain ratios from 25 to 155 s−1 were obtained. Then, from the bulk failure characteristics of the HPESA concrete materials under uniaxial impacting compression, the damage evolution mechanism of the material during its transformation from the structural phase to the damage phase was clarified, and an exponential model describing the evolution of damage with clear physical significance was obtained. Finally, when the damage variable of the HPESA concrete material was used in the Zhu-Wang-Tang (ZWT) rate-type constitutive equation, a uniaxial dynamic damage constitutive model that could describe the response of the HPESA concrete materials was obtained. The response characteristic parameters of the theoretical model were found by nonlinear fitting, which lays a foundation for numerical analysis of this material in underground engineering scenarios.