# Study on Mechanical Properties of Fractured Sandy Mudstone Based on Triaxial Compression Experiment
## 1 Introduction  
Complex geological conditions exist in coal mines that are mined underground. The rock is in its original three-way stress condition before mining and its stress state changes after mining. The major stress differential will cause rock fissures, which will subsequently result in tensile shear failure, diminishing the surrounding rock's stability and adversely affecting the safety of subterranean production [1; 2; 3; 4; 5; 6; 7]. Disasters including roof breakage, roof water inrush, and gas outbursts are among the mining operations mishaps that are directly linked to the formation of nearby rock fissures [8; 9; 10; 11; 12]. Studying the impact of fractures on the physical properties of the surrounding rock in slope is thus very important. Numerous tests and numerical simulation studies have been conducted to investigate the mechanical characteristics of fractured rock, primarily from two angles: varying loading techniques and varying fracture incidence. In his research, [PERSON] [13] examined the mechanical characteristics and compression failure forms of fractured rock bodies at varying loading rates. He discovered that, in cases where fracture occurrence is constant, the strength of the rock will increase as the loading rate increases, and that the strength of the rock is most affected by a fracture inclination angle of 30\({}^{\circ}\). The mechanical characteristics and energy changes of fractured rock under uniaxial compression were investigated by [PERSON] [14]. The findings indicated that the likelihood of tensile shear mixed failure inthe rock increases with the size of the fracture inclination. Prefabricated fractures reduced the energy storage limit of the rock specimens and had an impact on their rate of energy dissipation. [PERSON] [15] examined the strength and deformation characteristics of rock under various stress routes and investigated the impact of arc fractures on the mechanical properties of sandstone using traditional uniaxial compression and triaxial compression tests. The findings demonstrate that arc fractures have a higher peak strength under triaxial compression than they do with unloading confining pressure. The rock strength is weakened by the linear crack's arch height. [PERSON] [16] investigated the connection between rockburst and fracture incidence at open face using a prefabricated granite single crack experiment. The findings of the study indicate that the granite's strength is more degraded with a smaller crack dip angle and that the elastic energy produced by a rockburst decreases with increasing crack proximity to the open face. The elastic energy generated by the rock burst is clearly amplified when the crack is filled with resin. In a uniaxial experiment, [PERSON] et al. [17] investigated the stress-strain relationship of fractured rock. They discovered that the rock exhibits a bimodal form on the stress-strain curve under uniaxial pressure, that the fracture expansion has the optimal expansion Angle, and that tensile shear causes the majority of the rock's damage within this range. In order to simulate the complicated failure morphology of rock with fracture, [PERSON] [18] used an enhanced phase-field fracture model. He also conducted a theoretical analysis of the coupling connection between the phase field and the fracture displacement field. Regarding the occurrence of fractures, [PERSON] [19] investigated the mechanical characteristics of both intact and cross-fractured rock using a uniaxial compression experiment. The findings of the experiment demonstrated that the tensile inverse airfoil crack dominated the fracture development and that the peak strength and elastic modulus of the cross-fractured rock were relatively small under uniaxial compression. In order to characterize the geometry of granite blasting cracks, [PERSON] [20] integrated the SPH damage model with the finite element approach to determine the rock failure state and derive the real-time rock permeability.