实验技术与管理2025，Vol.42Issue(12)：19-25,7.DOI:10.16791/j.cnki.sjg.2025.12.003
不同加载路径下的泥岩强度特性试验研究
Experimental study on strength characteristics of mudstone under different loading paths
摘要
Abstract
[Objective]The timing of confining pressure application significant affects the ultimate mechanical properties of rock,and varying loading paths can result in substantial differences in rock and rock mass mechanical parameters.This study,based on the Guobo Station project,investigated the failure characteristics of mudstone and its mechanical parameters under two loading paths.The aim is to identify mechanical parameters that better align with actual engineering conditions,providing a theoretical basis for excavation stability analysis of this project and the design of surrounding rock support postexcavation,while offering valuable insights for similar projects.[Methods]This study combined laboratory triaxial tests with different strength criteria.Triaxial compression tests were performed under two loading paths:① simultaneous application of confining and axial pressures,and ② application of confining pressure first,followed by axial pressure.The failure characteristics and strength differences in mudstone under the two loading paths were analyzed.The Mohr-Coulomb criterion was utilized to evaluate the variance in mudstone mechanical parameters between loading paths.In addition,given the rock mass structural characteristics of the project site,the Hoek-Brown criterion was employed to convert the obtained rock block strength into rock mass strength,enabling a comparative analysis of rock mass mechanical parameters under different loading paths.[Results]Results revealed the following:① When the confining pressure(16 MPa)reached the uniaxial compressive strength of mudstone(16.87 MPa),the axial peak strength decreased by 41%compared with a confining pressure of 14 MPa;② Under both loading paths,the average mudstone failure angle θ was 65°,with cohesion 4.07-4.86 MPa and the internal friction angle 30.5°-41.7°;③ Under the Mohr-Coulomb criterion,the calculated cohesion of mudstone was 3.96 MPa and the internal friction angle was 40°;④ The uniaxial compressive strength increased exponentially with the GSI value,with an average uniaxial compressive strength of 0.82 MPa under simultaneous loading paths,compared with 0.65 MPa under the confining pressure-first and axial-pressure loading paths.The elastic modulus exhibited S-shaped growth,with an average value of 0.31 GPa.[Conclusions]The study derived the following conclusions:① Applying confining pressure first induced precracks in the rock,reducing peak strength.Thus,the triaxial compressive strength of mudstone was lower with preloading compared with simultaneous loading,with the degree of reduction correlated to the uniaxial compressive strength of the mudstone;② The deformation and failure characteristics of rocks under different loading paths showed minimal differences,with mudstone displaying clear elastoplastic deformation characteristics that ultimately result in shear failure;③ Preloading confining pressure reduced the internal friction angle of mudstone,whereas simultaneous loading was more representative of field conditions;④ As the GSI value increased,uniaxial compressive strength increased exponentially under both loading paths,and the elastic modulus exhibited S-shaped growth.关键词
岩石力学/三轴压缩试验/泥岩/加载路径/岩体强度Key words
rock mechanics/triaxial compression test/mudstone/loading path/rock mass strength分类
建筑与水利引用本文复制引用
ZHANG Huijian,WEI Zhongyu,FU Boyi,WANG Wen,WANG Lichuan,HU Jichun,LI Diyuan..不同加载路径下的泥岩强度特性试验研究[J].实验技术与管理,2025,42(12):19-25,7.基金项目
国家自然科学基金项目(52178395) （52178395）
中交第三公路工程局有限公司科技开发项目(101233021-JG-CQ07-0699-2024-0006) （101233021-JG-CQ07-0699-2024-0006）
中铁十八局集团有限公司科技开发项目(G23-07-S) （G23-07-S）
