Failure characterization of fully grouted rock bolts under triaxial testing
作者机构：Centre for Future Materials(CFM)School of EngineeringUniversity of Southern QueenslandToowoombaQLD4350Australia School of EngineeringUniversity of Southern QueenslandSpringfield CentralQLD4300Australia School of Civil EngineeringUniversity of QueenslandSt LuciaQLD4072Australia School of Surveying and Build EnvironmentUniversity of Southern QueenslandToowoombaQLD4350Australia School of CivilMining&Environmental EngineeringUniversity of WollongongWollongongNSW2500Australia
出 版 物：《Journal of Rock Mechanics and Geotechnical Engineering》 (岩石力学与岩土工程学报（英文版）)
年 卷 期：2024年第16卷第3期
页 面：778-789页
核心收录：
学科分类：08[工学] 081401[工学-岩土工程] 0818[工学-地质资源与地质工程] 0814[工学-土木工程]
基 金：Minova Australia University of Southern Queensland, USQ
主 题：Rock bolts Bolt-grout interface Bond strength Push test Triaxial tests
摘 要：Confining stresses serve as a pivotal determinant in shaping the behavior of grouted rock bolts.Nonetheless,prior investigations have oversimplified the three-dimensional stress state,primarily assuming hydrostatic stress conditions.Under these conditions,it is assumed that the intermediate principal stress(σ_(2))equals the minimum principal stress(σ_(3)).This assumption overlooks the potential variations in magnitudes of in situ stress conditions along all three directions near an underground opening where a rock bolt is installed.In this study,a series of push tests was meticulously conducted under triaxial conditions.These tests involved applying non-uniform confining stresses(σ_(2)≠σ_(3))to cubic specimens,aiming to unveil the previously overlooked influence of intermediate principal stresses on the strength properties of rock bolts.The results show that as the confining stresses increase from zero to higher levels,the pre-failure behavior changes from linear to nonlinear forms,resulting in an increase in initial stiffness from 2.08 kN/mm to 32.51 kN/mm.The load-displacement curves further illuminate distinct post-failure behavior at elevated levels of confining stresses,characterized by enhanced stiffness.Notably,the peak load capacity ranged from 27.9 kN to 46.5 kN as confining stresses advanced from σ_(2)=σ_(3)=0 to σ_(2)=20 MPa and σ_(3)=10 MPa.Additionally,the outcomes highlight an influence of confining stress on the lateral deformation of samples.Lower levels of confinement prompt overall dilation in lateral deformation,while higher confinements maintain a state of shrinkage.Furthermore,diverse failure modes have been identified,intricately tied to the arrangement of confining stresses.Lower confinements tend to induce a splitting mode of failure,whereas higher loads bring about a shift towards a pure interfacial shear-off and shear-crushed failure mechanism.
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