Abstract
With the increase of underground engineering construction depth,the phenomenon of surrounding rock sudden failure caused by supporting structure failure occurs frequently.The conventional unloading con-fining pressure (CUCP) test cannot simulate the plastic yielding and instantaneous unloading process of supporting structure to rock.Thus,a high stress loading-instantaneous unloading confining pressure (HSL-IUCP) test method was proposed and applied by considering bolt's fracture under stress.The wall thickness of confining pressure plates and the material of bolts were changed to realize different confin-ing pressure loading stiffness (CPLS) and lateral maximum allowable deformation (LMAD).The superio-rity of HSL-ICPU method is verified compared with CUCP.The rock failure mechanism caused by sudden failure of supporting structure is obtained.The results show that when CPLS increases from 1.35 to 2.33 GN/m,rock's peak strength and elastic modulus increase by 25.18％ and 23.70％,respectively.The fracture characteristics change from tensile failure to tensile-shear mixed failure.When LMAD decreases from 0.40 to 0.16 mm,rock's residual strength,peak strain,and residual strain decrease by 91.80％,16.94％,and 21.92％,respectively,and post-peak drop modulus increases by 140.47％.The test results obtained by this method are closer to rock's real mechanical response characteristics compared with CUCP.
维普
万方数据