Unconfined compressive strength and failure behaviour of completely weathered granite from a fault zone  

作　　者：DU Shaohua MA Jinyin MA Liyao ZHAO Yaqian 

机构地区：[1]School of Civil Engineering and Architecture,Henan University of Science and Technology,Luoyang 471023,China [2]School of Resources and Safety Engineering,Central South University,Changsha 410083,China [3]China Railway 18th Bureau Group Co.,Ltd,Tianjin 300222 China [4]China General Nuclear Power Corporation,Shenzhen 518031,China

出　　处：《Journal of Mountain Science》2024年第6期2140-2158,共19页山地科学学报（英文）

基　　金：supported by the National Natural Science Foundation of China,NSFC(No.42202318).

摘　　要：Understanding the strength characteristics and deformation behaviour of the tunnel surrounding rock in a fault zone is significant for tunnel stability evaluation.In this study,a series of unconfined compression tests were conducted to investigate the mechanical characteristics and failure behaviour of completely weathered granite(CWG)from a fault zone,considering with height-diameter(h/d)ratio,dry densities(ρd)and moisture contents(ω).Based on the experimental results,a regression mathematical model of unconfined compressive strength(UCS)for CWG was developed using the Multiple Nonlinear Regression method(MNLR).The research results indicated that the UCS of the specimen with a h/d ratio of 0.6 decreased with the increase ofω.When the h/d ratio increased to 1.0,the UCS increasedωwith up to 10.5%and then decreased.Increasingρd is conducive to the improvement of the UCS at anyω.The deformation and rupture process as well as final failure modes of the specimen are controlled by h/d ratio,ρd andω,and the h/d ratio is the dominant factor affecting the final failure mode,followed byωandρd.The specimens with different h/d ratio exhibited completely different fracture mode,i.e.,typical splitting failure(h/d=0.6)and shear failure(h/d=1.0).By comparing the experimental results,this regression model for predicting UCS is accurate and reliable,and the h/d ratio is the dominant factor affecting the UCS of CWG,followed byρd and thenω.These findings provide important references for maintenance of the tunnel crossing other fault fractured zones,especially at low confining pressure or unconfined condition.

关 键 词：Fault fracture zone Completely weathered granite(CWG) Unconfined compression strength(UCS) Multiple nonlinear regression model 

分 类 号：U452.11[建筑科学—桥梁与隧道工程]