Hydraulic fracturing of cylindrical concrete bodies in a non-uniform stress field

An experimental study of the hydraulic fracture of thick-walled cylinders with the application of a diametrical load was carried out on specimens in the form of cylinders with a central circular hole and a circular hole located at a distance of half the radius from the center of the cylinder at an angle of 45 degrees to the load application line. Specimens were made of concrete based on aluminous cement. Ultimate stresses in the material were determined for two types of stress state: under tension in bending conditions and under a compound stress state on the surface of the hole. The modeling of the fracturing process taking into account the inhomogeneity of the stress state near the hole was carried out using the boundary elements method (in the variant of the fictitious load method) and the gradient fracture criterion. Calculation results of the ultimate pressure were compared with experimental data. Experimental study showed scale effect in concrete specimens with stress concentrators.