Experimental characterization of dynamic strength and failure behavior of saturated reef limestone concrete under biaxial stress constraint

Abstract

On the basis of not destroying the island's ecological environment, concrete mixed with reef limestone aggregates in situ is beneficial to solve the problem of shortage of terrestrial rock resources in the island area. Considering the influence of water-saturated state, lateral stress constraint and strain rate, the dynamic mechanical properties and failure characteristics of reef limestone concrete under biaxial stress constraint are studied by using true triaxial Hopkinson bar test technology. The dynamic failure behavior of reef limestone concrete is analyzed from macro-meso level by means of SEM test method, and the stress intensity factor theory of crack tip is cited to reveal the enhancement effect of dynamic strength of water-saturated reef limestone concrete under the coupling effect of biaxial stress constraint and impact load. The results show that the dynamic compressive strength of reef limestone concrete increases with the strain rate in a power function, and the growth rate decreases gradually. Under the same impact load, the compressive strength of reef limestone concrete in water-saturated state increases more significantly than that in dry state. The lateral stress constraint has a significant enhancement effect on the dynamic strength of reef limestone concrete samples, and changes the Poisson's ratio of reef limestone concrete samples. In addition, based on the equivalent crack model theory, it is verified that under the combined action of biaxial stress constraint and high strain rate, the dynamic stress intensity factor of the crack tip of the reef limestone concrete sample in water-saturated state is larger than that in dry state.