Failure characterization of fully grouted rock bolts under triaxial testing  

作　　者：Hadi Nourizadeh Ali Mirzaghorbanali Mehdi Serati Elamin Mutaz Kevin McDougall Naj Aziz 

机构地区：[1]Centre for Future Materials(CFM),School of Engineering,University of Southern Queensland,Toowoomba,QLD,4350,Australia [2]School of Engineering,University of Southern Queensland,Springfield Central,QLD,4300,Australia [3]School of Civil Engineering,University of Queensland,St Lucia,QLD,4072,Australia [4]School of Surveying and Build Environment,University of Southern Queensland,Toowoomba,QLD,4350,Australia [5]School of Civil,Mining&Environmental Engineering,University of Wollongong,Wollongong,NSW,2500,Australia

出　　处：《Journal of Rock Mechanics and Geotechnical Engineering》2024年第3期778-789,共12页岩石力学与岩土工程学报（英文版）

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.

关 键 词：Rock bolts Bolt-grout interface Bond strength Push test Triaxial tests 

分 类 号：TU476[建筑科学—结构工程]