In the present paper, a numerical model for deformation and fracturing of brittle rocks is used to study the damage evolution and localized fracturing of brittle rocks based on statistical mesoscopic damage mechanics. In the model, material heterogeneity and the mesoscopic renormalization concept are introduced to consider the interaction among microcracks in rock. The temporal and spatial evolution of acoustic emissions in the stressed rock are also described. Correspondingly, numerical tests on rock specimens with different heterogeneities, porosities, and scales are performed to investigate the damage evolution and localized fracturing of brittle rocks. The localized damage and fracturing of brittle rocks induced by microstructural damage is investigated. The study shows that heterogeneity, porosities, and scales of rock specimen have significant impact on damage evolution and localized fracturing mode. In addition, the study reveals that the postpeak response of stress-strain curve is due to the deformation of the structural elements, and localization means that the descending branch of the stress-strain curve of the rock specimen is size dependent, and the stress-strain curve can therefore not be regarded as a pure material property.

In this paper, a model for damage and fracture, considering the heterogeneity of material properties, is validated and used to investigate the mechanism of spallation in fiber-reinforced concrete (FRC) slabs with various fiber and aggregate contents under impact loading. Numerical simulations show that there is a marked difference in the failure patterns among slabs with various fiber and aggregate contents, and the fibers can remarkably improve the tensile strength of the concrete slab, effectively prevent the initiation and propagation of cracks, and inhibit the occurrence of spallation. Moreover, numerical simulations capture the whole process of the propagation of incident compressive stress waves in the FRC and the reflection of stress waves upon concrete surfaces and the spallation failure of FRC induced by the reflected tensile stress wave, which is obviously different from the failure pattern of FRC under static loads. The results of this study can also provide a valuable reference for studies on the tensile properties and failure modes of heterogeneous quasi-brittle materials and the design of FRC slabs with appropriate fiber contents.

In this paper, localized damage and failure process of brittle rock in compression is investigated using rock failure process analysis (RFPA) model. The model accounts for material heterogeneity to capture the cooperative interaction between microcracks in the transition from distributed to localized damage and the temporal and spatial evolution of acoustic emission during the progressive damage process. Correspondingly, a series of numerical compressive tests on rock specimens are performed to investigate the damage evolution and localized fracturing of brittle rock. The study shows that heterogeneity and scale of specimen have significant effect on damage localization and failure mode of rock specimens. In addition, post-peak response of stress-strain curve is due to the deformation of the structural elements, and localization means that the descending branch of the stress-strain curve of specimen is size dependent and the stress-strain curve can therefore not be regarded as a pure material property.