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该文以重庆地区铁路车站工程中的泥岩试样为研究对象，开展了两种不同加载路径（研究同步施加围压轴压、先施加围压后施加轴压）下的力学特性试验，研究两种加载方案下泥岩破坏特征和力学参数差异，并探讨了依托工程区域岩石和岩体强度差异。研究结果表明：先施加围压会导致其三轴抗压强度低于同步加载方式，降低程度与泥岩单轴抗压强度相关；两种加载方案下的泥岩均呈现明显弹塑性变形特征，且最终均发展为剪切破坏；先加载围压会导致泥岩内摩擦角降低，同步加载方式更符合现场实际；随GSI值增加，两种加载方式下的单轴抗压强度呈指数增长，弹性模量呈S型增长。研究成果可为室内三轴试验操作及类似工程提供参考。
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.
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基本信息:
DOI：10.16791/j.cnki.sjg.2025.12.003
中图分类号:TU45
引用信息:
[1]章慧健,魏中雨,付柏毅,等.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.DOI:10.16791/j.cnki.sjg.2025.12.003.
基金信息:
国家自然科学基金项目(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); 中铁十八局集团有限公司科技开发项目(G23-07-S)