Static And Dynamic Mechanical Properties And Energy Release Characteristics Of Granite From Various Burial Depths

The exploitation of mineral resources is gradually moving from the shallow to deep levels.Mechanical properties of rock play a basic and important role in rock dynamic disaster prevention and control as well as rock engineering design and construction.However,the corresponding basic theoretical research has not refined the differences in rock mining engineering at different depths.To study the mechanical properties and energy evolution rules during rock failure at different buried depth,static loading experiments under uniaxial compression and dynamic impact experiments at different strain rates and confining pressures were carried out on six groups of granite specimens with different buried depth.The results indicate that:(1)The composition and physical properties of granite samples with different buried depths have certain differences with the depth of occurrence.These differences further lead to the differences in macrophysical and mechanical properties of granite samples.These studies provide necessary for subsequent research.(2)In uniaxial compression test and dynamic impact test,the relationships between the secant modulus,peak stress,elastic modulus,brittleness index,and the burial depth is basically in line with the quadratic function.(3)In uniaxial compression experiments,the dissipation energy and energy dissipation rate of rocks show a quadratic curve with the increase of the depth.Moreover,the amount of the dissipation energy during the rock failure is closely related to the buried depth of the rock specimens.(4)In dynamic loading impact experiments,the incident energy,transmitted energy,dissipation energy and absorption energy increase with the rising strain rate and confining pressure.The reflected energy of rock specimens go up with the increase of the strain rate,while they decrease with the rising confining pressure.(5)In the uniaxial compression test,the rock failure pattern was mostly tensile failure.In the dynamic loading experiments at various strain rates,when the strain rate is small,the failure pattern of the rock changes with the buried depth,showing the following patterns: local instability,overall instability,local instability.Furthermore,when the strain rate increases,the failure pattern transforms into overall instability.In the dynamic impact experiments with different confining pressures,because the confining pressure restricts the lateral deformation of the rock sample,the rock only undergoes shear failure.(6)As the strain rate gets larger and larger,the fractal dimension D increases gradually.The growth amplitude of D for the deep rock specimen is significantly greater than that for the shallow one.The specimen fragmentation degree is smaller and smaller,and the fragment particle size gets more and more uniform.