Effect of bedding dip angle on the fracturing behavior of mudstone in uniaxial compression

REN Jianchao; ZHANG Hu; MA Yinghui; SUN Liqiang; LIU Qianjin; ZHAO Tielin

doi:10.11799/ce202512020

Abstract：Aiming at the influence of mudstone bedding inclination on its mechanical behavior and rupture response characteristics,taking mudstone specimens from Caojiatan Coal Mine of Shaanxi Coal mine as the research object,laboratory tests and discrete element numerical simulation were used to explore the influence of bedding dip angle on mudstone mechanical behavior and its relationship with macroscopic crack evolution characteristics.Firstly,uniaxial compression tests were carried out on mudstone specimens with different bedding dip angles(0°,15°and 30°).It was found that with the increase of bedding dip angle,the compressive strength of specimens under uniaxial compression decreased,the large penetrating cracks that dominated the macro-failure of specimens tilted to the horizontal direction,and the failure mode of rock mass gradually changed from brittle failure to ductile failure.In order to deeply explore the effects of weak bedding structure on the mechanical properties of mudstone specimens and the evolution law of microcracks,numerical models of different bedding angles(0°～90°)were established by using discrete element PFC numerical simulation software,and the weak bedding structure plane was realized by layering modeling and weakening the bonding contact parameters of interlayer particles.The results show that the uniaxial compressive peak stress,peak strain and elastic modulus of stratified mudstone first decrease and then increase with the increase of dip angle.In the process of loading failure,micro-cracks occur first on the weak structural plane of bedding,the pre-cutting effect of bedding is obvious,and the generation and propagation attitude of large penetrating cracks are also controlled by the angle of bedding plane.It shows that the existence of bedding structural plane has a significant deterioration effect on the bearing capacity of mudstone,and the influence of bedding dip angle on the stability of surrounding rock and the early warning of the failure of rock bedding structure should be fully considered in the control of underground roadway surrounding rock.