Experimental Study on Anisotropy of Strength, Deformation and Damage Evolution of Contact Zone Composite Rock with DIC and AE Techniques

Compared to general anisotropic rocks, the contact zone composite rock composed of strong and weak rocks has distinct characteristics in terms of structure and physical and mechanical properties. The uniaxial compression test of composite specimens with different degrees of material difference lambda and interface inclination angle theta = 0 degrees similar to 9 0 degrees were carried out to study the effect of material difference and inclination angle on the anisotropy of strength, deformation and damage evolution with acoustic emission (AE) and digital image correlation (DIC) techniques. The results show that the UCS, elastic modulus, sigma(ci) , and sigma(cd) of the composite specimen roughly show U-shaped anisotropy. The damage evolution characteristics of two materials and inclined interface vary regularly with the inclination angle. There is differential deformation between the two materials, which forms the relative sliding tendency between the materials that changes with the inclination angle. The degree of relative sliding at different angles is 60 degrees > 45 degrees > 75 degrees > 90 degrees > 30 degrees > 0 degrees. The composite specimen has three types of failure modes: weak material failure mode (0 degrees similar to 30 degrees), interface shear mode (60 degrees) and composite mode (45 degrees, 75 degrees similar to 90 degrees). The anisotropy of the composite specimen is comprehensively affected by material difference and inclination angle. Increasing the material difference will increase the differential deformation and damage and relative sliding tendency between materials. Increasing the inclination angle will increase the shear stress on the interface and weaken the differential deformation and damage. Material difference affects the interface strength, which in turn affects the ability of the interface to resist shear failure and relative sliding.

Automated summary

The anisotropy of composite rocks is affected by material difference and inclination angle, with differential deformation, damage, and relative sliding tendency increasing with higher material difference and inclination angle. Different failure modes exist in composite specimens at different angles.