Influence of hole diameter on mechanical properties and stability of granite rock surrounding tunnels

Nowadays, the development and utilization of more engineering construction are closely related to granite. However, many granite rock masses in Qingdao contain natural hole defects, which have a great impact on mechanical properties It may even cause instability surrounding safety accidents. Therefore, this paper, we discuss influence diameter stability tunnels. Uniaxial compression experiments were conducted with different diameters, monitoring was carried out using acoustic emission system XTDIC (Xintuo 3D Digital Image Correlation) three-dimensional–full-field strain-measurement systems. The relationship between strength, deformation, size investigated. In addition, Yangkou tunnel as prototype PFC2D (Particle Flow Code 2D) particle-flow–numerical-simulation program, working model sizes established simulate defect rock. results show that: (1) an increase diameter, uniaxial compressive strength elastic modulus sample gradually decreased. brittleness samples decreased, ductility increased. (2) Under action axial stress likely produce concentration around defect, increased deformation localization band, development, expansion, well intersection degree. As result, develop new cracks. These cracks number size, reducing sample. (3) defects significantly affected damage When increasing area tensile near localized became evident. reduced, its bearing capacity weakened, leading easier crack initiation damage.