Mechanical properties and damage constitutive model of basalt fibre-reinforced coral concrete under compression-shear loading

The mechanical properties of basalt fibre-reinforced coral concrete under compression-shear loading are investigated utilizing the RMT-201 rock mechanics test system, and the relevant failure criteria and damage constitutive model are established based on the experimental results. The results show that the shear stress-strain curve of basalt fibre-reinforced coral concrete can be divided into four stages. Peak shear stress, peak shear strain, and initial shear modulus can be improved by increasing the compressive stress ratio and adding basalt fibres. The above compression-shear properties are positively correlated with the compressive stress ratio and tend to increase and then decrease with the increase of basalt fibre content, and the optimum fibre content is 0.8 %. In addition, the incorporation of basalt fibres decreases the roughness of the shear surface. The failure criteria are established based on octahedral stress, stress invariance, and unified twin shear strength theory, with the criteria based on stress invariance exhibiting the highest accuracy. Finally, a Weibull distribution model is introduced to describe the damage evolution process of basalt fibre-reinforced coral concrete, and an associated shear damage constitutive model is proposed, which is in good agreement with the experimental results, and the physical significance of the model parameters is explicit. This study is significant for understanding the compressive shear characteristics of basalt fibre-reinforced coral concrete and for promoting its application in marine structural engineering.