An innovative test method for mechanical properties of sandstone under instantaneous unloading confining pressure  

作　　者：Xuesheng Liu Shenglong Yang Yunliang Tan Jun Wang Xuebin Li Yu Zhang 

机构地区：[1]College of Energy and Mining Engineering,Shandong University of Science and Technology,Qingdao 266590,China [2]State Key Laboratory of Mining Disaster Prevention and Control,Shandong University of Science and Technology,Qingdao 266590,China [3]Geoscience Department,Nuclear Waste Management Organization,Canada

出　　处：《International Journal of Mining Science and Technology》2024年第12期1677-1692,共16页矿业科学技术学报（英文版）

基　　金：the National Natural Science Foundation of China(Nos.52374218,52174122 and 52374094);Outstanding Youth Fund of Shandong Natural Science Foundation(No.ZR2022YQ49);Taishan Scholar Project in Shandong Province(Nos.tspd20210313 and tsqn202211150).

摘　　要：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.

关 键 词：High stress Instantaneous unloading confining pressure Test method Confining pressure loading stiffness Lateral maximum allowable deformation Rock properties 

分 类 号：TU45[建筑科学—岩土工程] U451.2[建筑科学—土工工程]