Mechanical characteristics and energy dissipation characteristics of dredged sand concrete during triaxial loading

During the service period, the concrete structures such as water gates, dams and concrete offshore platforms are often in a complex stress state such as triaxial loading. Therefore, it is very necessary to explore the force of concrete with different dredged sand contents under triaxial loading. In this paper, the failure modes of dredged sand concrete under different confining pressures were analyzed firstly. And then the mechanical property was explored. Finally, combined with CT technology, the three-dimensional structure of the fractured sample was reconstructed to realize the 3D visualization and the energy evolution mechanism of concrete triaxial monotonic compression under different confining pressures was explored. The results showed that the residual stress of concrete under triaxial cyclic loading was smaller than that under monotonic loading. According to Mohr-Coulomb failure criterion, the prediction failure angle of the sample is generally 66.1°–77.1°. With the increase of loading times, the energy loss developed more slowly, and the elastic modulus of loading and unloading decreased slightly. The calculation results of the parameterized constitutive equations of concrete under triaxial compression were in good agreement with the experimental results. Concrete was seriously damaged under the condition of low confining pressure and cyclic loading. Before the peak stress, the concrete samples mainly stored elastic energy. •Dredged sand used in concrete as a substitute for machine-made sand.•Cracks distributed in different ways according to the confining pressure.•The replacement rate of dredged sand affected the basic mechanical properties of concrete.•3D visualization and calculation of the internal cracks and pores combined with CT technology.•Specimen mainly stored elastic energy before the peak stress.