Numerical and experimental study of the mechanical behaviour for FRP-wrapped cement mortar-coal composite disc

The instability of the interface could induce the failure of the composite structure, and fibre-reinforced polymer (FRP) can be applied to solve this problem. The effect of FRP wrapping on the tensile strength and failure pattern of the cement mortar-coal composite (CCC) disc at different interface angles were investigated by the Brazilian splitting experiment. The effect of FRP wrapping on microcracks and contact force evolution was further revealed through PFC3D-FLAC3D coupling numerical simulation, and the mechanism of FRP wrapping was demonstrated. The results indicate that FRP wrapping significantly improved the nominal tensile strength of the specimens. In addition, FRP wrapping reduced the anisotropy of the specimens. Three types of failure were observed in the composite specimens: fractures in the coal and cement mortar elements were tensile cracks, while fractures at the interface were shear or tensile. FRP wrapping increased the degree of damage to the coal and cement mortar elements when the specimen was unstable, but reduced the extent of damage at the interface. The degree and extent of the stress concentration were increased with FRP wrapping, and the anisotropy of the contact force distribution was reduced.

Automated summary

FRP wrapping can improve the tensile strength of cement mortar-coal composite (CCC) by reducing the instability of the interface and modifying the failure pattern. The experimental and numerical simulation results show that FRP wrapping significantly enhances the nominal tensile strength of the specimens and reduces their anisotropy. Three types of failure modes are observed: tensile cracks in the coal and cement mortar elements, and shear or tensile fractures at the interface. FRP wrapping increases the damage degree of the coal and cement mortar elements in unstable specimens, but decreases the extent of damage at the interface.