以宜昌—巴东高速公路凉水井隧道出露的石膏质围岩为研究对象,开展了不同含水率、不同干湿循环下的石膏质岩单轴压缩试验,探讨其强度软化特性。利用微观电镜扫描石膏质岩遇水及干湿循环后微观结构,分析其强度劣化机理。结果表明:石膏质岩强度较低,属于软岩,强度及变形指标随含水率变化十分敏感,遇水软化特性显著,试样的抗压强度、弹性模量、变形模量都随着含水率的增大而降低,并与含水率呈现良好的函数关系,泊松比随着含水率的增大而近似呈现增大的趋势;干湿循环作用对石膏质岩力学性质劣化明显,抗压强度、弹性模量、变形模量随着干湿循环次数的增加而不断降低,并与干湿循环次数呈现良好的对数关系,泊松比随着干湿循环次数的增加而增大,但增幅有限;微观电镜图片显示水对石膏质岩结构破坏特征显著。石膏质岩的不良特性将对隧道建设产生不利影响,隧道施工中注意采取相应的防治措施。
Abstract
In this article, gypsiferous surrounding rock exposed in Liangshuijing tunnel area of the Yichang-Badong expressway is taken as the research object by uniaxial compression test and scanning electron microscope test to explore the softening behavior and strength degradation mechanism of gypsum rock under different moisture contents and drying and wetting cycles. The research results indicate that the gypsum rock’s strength and deformation index are very sensitive to moisture content. It is soft rock with low compressive strength and has obvious softening characteristic in water. The mechanical parameters including uniaxial compressive strength, elastic modulus, and deformation modulus reduce with the increase of moisture content in rock, displaying a good function relationship; whereas Poisson’s ratio approximately increases with the increase of moisture content. The drying and wetting cycles have an obvious effect on the degradation of gypsum rock’s mechanical properties. The uniaxial compressive strength, elastic modulus, and deformation modulus reduce with the increased times of drying and wetting cycles, showing a good logarithmic relationship; while Poisson’s ratio increases slightly with the increased times of drying and wetting cycles. The microscanning images show that water is obviously destructive to the structure of gypsum rock. Corresponding prevention and control measures should be taken during the tunnel construction to prevent the adverse effects of bad characteristics of gypsum rock.
关键词
隧道围岩 /
石膏质岩 /
含水率 /
干湿循环 /
单轴压缩 /
微观电镜扫描
Key words
tunnel’s surrounding rock /
gypsum rock /
moisture content /
drying and wetting cycle /
uniaxial compression /
scanning electron microscope
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参考文献
[1] RUTTER E H. The Influence of Temperature, Strain Rate and Interstitial Water in the Experimental Deformation of Calcite Rocks[J] . Teotonophysics,1974, 22(3/4):311-334.
[2] GLOVER P W J, GOMEZ J B. Damage of Saturated Rocks under Going Triaxial Deformation Using Complex Electrical Conductivity Measurements: Experimental Results[J] . Physics and Chemistry of the Earth, 1997, 22(1/2): 57-61.
[3] 韦立德,徐卫亚,邵建富.饱和非饱和岩石损伤软化统计本构模型[J] .水利水运工程学报,2003,(2):12-17. (WEI Li-de, XU Wei-ya, SHAO Jian-fu. Statistical Damage-Softening Constitutive Model for Saturated and Unsaturated rock[J] . Hydro-science and Engineering, 2003,(2): 12-17. (in Chinese)
[4] HADIZADEH J. Water-Weakening of Sandstone and Quartzite Deformed at Various Stress and Strain Rates[J] . International Journal of Rock Mechanics and Mining Sciences, 1991, 28(5): 431-439.
[5] 杨天鸿,唐春安,冯启言.孔隙水压作用下岩样加载破坏工程的数值模拟[J] .岩土力学,2001,22(4):378-382. (YANG Tian-hong, TANG Chun-an, FENG Qi-yan. Numerical Simulation on Progressive Failure of Loaded Rock Sample under Pore Hydraulic Pressure[J] .Rock and Soil Mechanics,2001,22(4):378-382. (in Chinese)
[6] 陈钢林,周仁德. 水对受力岩石变形破坏宏观力学效应的试验研究[J] . 地球物理学报,1991,34(3):335-341. (CHEN Gang-lin,ZHOU Ren-de. An Experimental Study Concerning the Macro-scopic Effect of Water on the Deformation and Failure of Loaded Rocks[J] .Acta Geophysica Sinica,1991,34(3):335-341. (in Chinese)
[7] 谢和平,陈中辉.岩石力学[M] .北京:科学出版社,2004.(XIE He-ping, CHEN Zhong-hui. Rock Mechanics[M] . Beijing: Science Press, 2004. (in Chinese)
[8] 彭曙光,裴世聪.水岩作用对岩石抗压强度效应及形貌指标的实验研究[J] .实验力学,2010,25(3):365-370.(PENG Shu-guang, PEI Shi-cong. Experimental Study of Compression Strength and Micro-topography Description Index for Groundwater Saturated Rock[J] . Journal of Experimental Mechanics,2010,25(3):365-370. (in Chinese)
基金
国家自然科学基金项目(41272377);交通运输部联合科技攻关项目(2009-353-342-540)
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