Experimental Study Of Mechanical Characteristics Of Green Sandstone With Initial Damage Under Uniaxial Creep-Impact Loading

In the deep underground mining,rock under high crustal stress exhibits obvious creep behavior.Meanwhile,the dynamic disturbance from rock drilling and explosive blasting will influence rock.So,the rock in deep underground mining is under the combination of long-term quasi-load and dynamic disturbance.The interaction of long-term quasi-load and dynamic disturbance play a key role in the deformation and damage evolution of rock.Understanding the damage evolution and fracture process of rock is of great importance for evaluating the engineering stability and safety,and for optimizing the supporting parameters.In addition,in underground mining with drilling and blasting method,the mechanical property of surrounding rock will be degraded that leading to the creation of and excavation damaged zone,which is composed with rock with different degree of damage.Recognizing the damage evolution and fracture process of rock with different degree of damage is also critical for deep underground mining.Therefore,the present paper begins with the characterization of the P-wave velocity,energy dissipation,deformation and microstructure of the rock specimen with different impact damage by the split Hopkinson pressure bar device driven by a pendulum hammer.Then,uniaxial compression test was conducted to get the creep stress.Conventional uniaxial creep test was performed to study the influence of initial damage on the creep strain rate and failure time.Secondly,the creep-impact test was carried out using the rheology-disturbance test machine to study the creep stress level and impact energy on the deformation behavior during the impact process and the failure time,creep deformation and acoustic emission after dynamic disturbance.Thirdly,the creep-impact tests of intact rock specimen and damage rock specimen were carried out to study the influence of initial damage on the deformation behavior during impact process and the failure time,creep deformation and acoustic emission during the creep after dynamic disturbance.Finally,the creep-impact tests of damage rock specimen was carried out to study the influence of impact energy on the deformation behavior during impact process and the failure time,creep deformation and acoustic emission during the creep after dynamic disturbance.