Effect of Lithology on Mechanical and Damage Behaviors of Concrete in Concrete-Rock Combined Specimen

Abstract

A concrete structure built on rock foundation works together with the connected rock mass, which has a significant effect on the mechanical behaviors of the concrete structure. To study the effect of lithology on the mechanical and damage behaviors of concrete in a concrete-rock combined specimen (CRCS), first, a test method for measuring the concrete part (concrete in CRCS) is adopted, then, uniaxial compression tests on seven types of specimens are performed and acoustic emission (AE) events are simultaneously monitored. Test results show that the low-strength concrete part plays a major role in the fracture behavior of CRCS. When the CRCS is failed, a sudden stress drop happens in CRCS, and the rock part (rock in CRCS) experiences a rapid axial strain recovery and intensifies the failure of the concrete part. The load-bearing and deformation capacities of the concrete part increase with the strength of the rock part, but the rock part shows the opposite behaviors under the influence of the concrete part. Furthermore, the damage of CRCS is mainly formed in the concrete part, and the damage extent of the concrete part is positively correlated with the strength of the rock part. Finally, a damage constitutive model of the concrete part is established and validated. This model can be used to accurately describe the effect of lithology on the mechanical response of the concrete part under uniaxial compression loading.