Tensile stress concentration and compressive failure in cemented granular material

Grain crushing and pore collapse are important micromechanical processes responsible for hydrostatic and shear‐enhanced compactions in porous rocks. These processes initiate from extensile microcracks which emanate from grain contacts. Microstructural observations indicate that such extensile cracking is inhibited in the vicinity of cemented grain contacts. The finite element technique was used to simulate the tensile stress concentration and normal stiffness in a cemented aggregate. The detrital grains were assumed to be elastically identical spheres bonded by cement layers of finite thickness. The numerical simulations show that the maximum tensile stress concentration is located near the triple junction (among grain, cement and pore space), and its magnitude is significantly less than that for an uncemented system. The development of microcracking near a cemented contact is readily inhibited unless the applied stress exceeds a critical value which is at least an order of magnitude greater than that for the onset of Hertzian fracture.