摘要
深部煤巷工程煤岩体在开挖诱发的卸荷作用下,易因蠕变变形和力学性质劣化引起煤巷围岩大变形,进而威胁地下工程服役期间的长期稳定性.为揭示深部煤岩在开挖卸荷后的蠕变特性与破坏特征,通过三轴压缩试验确定分级卸荷的初始围压及各级卸载水平,在相同初始围压(25 MPa)下,开展不同轴压条件下的卸荷蠕变试验,系统分析煤岩在卸荷过程中的蠕变变形、破坏特征及能量耗散规律.试验结果表明:随着偏应力增大,试样的蠕变应变和应变速率逐渐上升.轴向应力增大时,试样的破坏模式由剪切破坏转变为以张拉破坏为主的拉剪复合破坏.随着卸荷过程的进行,试样吸收的总能量和耗散能呈现明显的阶梯状上升,而弹性应变能则因侧向约束减弱而呈现阶梯状下降.轴压增大时,试样吸收的能量增加,导致微裂纹的形成与宏观破碎程度加剧,碎块数量显著增加.
Deep coal roadway engineering coal rock mass is prone to large deformation of the surrounding rock due to creep deformation and mechanical property degradation under the unloading effect induced by excavation,thereby threatening the long-term stability of underground engineering during service.To reveal the creep characteristics and failure characteristics of deep coal rock after excavation unloading,this study first determined the initial confining pressure and each unloading level of graded unloading through triaxial compression tests.Then,under the same initial confining pressure(25 MPa),unloading creep tests under different axial pressure conditions were carried out,and the creep deformation,failure characteristics,and energy dissipation patterns of coal rock during the unloading process were systematically analyzed.The results show that as deviatoric stress increases,both creep strain and strain rate increase.With increasing axial stress,the failure mode transitions from shear failure to a tensile-shear combined failure,with tensile failure transitions from shear failure to a tensile-shear combined failure,with tensile failure becoming dominant.The total energy absorbed and dissipated by the sample increases in distinct stepwise increments with each unloading stage,while the elastic strain energy decreases stepwise due to the reduction in lateral confinement.As axial pressure increases,the energy absorbed by the sample also increases,leading to the generation of microcracks and an intensified degree of macroscopic fragmentation,accompanied by a significant increase in the number of broken fragments.
作者
徐春辉
苏晓晓
蔚立元
孙贤会
石美霞
谢子涵
张站群
XU Chunhui;SU Xiaoxiao;YU Liyuan;SUN Xianhui;SHI Meixia;XIE Zihan;ZHANG Zhanqun(Wangjialing Mine,China Coal Huajin Group Company Limited,Yuncheng 043300,Shanxi,China;State Key Laboratory of Intelligent Construction and Healthy Operation and Maintenance of Deep Underground Engineering,China University of Mining and Technology,Xuzhou 221116,Jiangsu,China;Institute of Water Engineering Sciences,Wuhan University,Wuhan 430072,China)
出处
《昆明理工大学学报(自然科学版)》
北大核心
2025年第6期35-44,共10页
Journal of Kunming University of Science and Technology(Natural Science)
基金
国家自然科学基金项目(52179118)。
关键词
岩石力学
深部煤岩
三轴卸荷
蠕变试验
能量演化
Rock mechanics
deep coal
triaxial unloading
creep experiment
energy evolution
