Fatigue behavior investigation of artificial rock under cyclic loading by using discrete element method

•Pioneering research in the domain of rock mechanics, offering a multidimensional examination of artificial rock fatigue behavior under diverse cyclic loading conditions.•A comprehensive investigation, encompassing three groups of cylindrical concrete specimens, to uncover the influence of material strength on fatigue response.•Introduction of the Stress-life (S-N) model as a novel approach to describe rock fatigue behavior, culminating in a robust equation that enhances our grasp of this complex phenomenon.•Distinctive insights into the evolution of fracture and geometries under cyclic loading, showcasing how fractures are distributed extensively throughout the specimen volume.•Recognition of the porosity variable as a valuable descriptor for characterizing the rock damage process provides a novel perspective on fatigue-induced damage in rocks. In numerous engineering projects, such as tunnel construction, underground gas storage in caverns, and the impact of earthquakes, rock materials experience cyclic loading. However, the response of rock materials to cyclic loading, which may vary in terms of waveform, frequency, and amplitude, is not uniform. Consequently, comprehending the mechanical attributes and fatigue behavior of rocks holds significant importance in engineering designs. This study focuses on subjecting a collection of cylindrical concrete specimens, categorized into three groups with distinct mechanical properties, to both monotonic and cyclic loading within a laboratory environment. Three groups of cylindrical concrete samples with different mixing designs are prepared to evaluate the effect of the mechanical strength of the samples on the fatigue response of the rock. In such a way that: The first group (G1) with Uniaxial Compressive Strength (UCS): 19 MPa, the second group (G2) with (UCS): 49 MPa, and the third group (G3) with (UCS): 71 MPa. In addition, the discrete element method is utilized to simulate uniaxial cyclic compression tests under various loading conditions, such as monotonic and cyclic loading. The resulting fracture propagation patterns and geometries are then analyzed. Numerical and experimental results show that the cyclic uniaxial compressive strength, due to the presence of damage and fatigue phenomena, has decreased relative to the monotonic tests. Also the cyclic elastic modulus values (Ec) have decreased by 53 %, 25 %, and 11 % relative to the monotonic elastic modulus (Em) for the three groups of G1, G2, and G3, res