水库在建成运营过程中,水库内水位反复升降对库岸边坡安全性产生影响。为探究饱水-风干循环作用下水库边坡岩体力学性质的劣化规律,以某水库边坡水位变幅带砂岩为试验对象,进行岩石三轴压缩试验。引入劣化率概念探究水岩作用对砂岩力学性质的影响,并借助电镜扫描技术分析了砂岩在水岩作用下的劣化机理。研究表明:水岩作用程度相同时,砂岩峰值抗压强度随围压增大而变大;相同围压条件下,随饱水-风干/循环次数增多,砂岩峰值抗压强度、黏聚力、内摩擦角变小,且三者数值与循环次数N之间的变化规律符合指数分布。当水岩作用增强时,峰值抗压强度劣化率最小值为31.35%,黏聚力、内摩擦角劣化率分别为30.61%和15.37%;水库水位升降对砂岩峰值抗压强度、黏聚力影响较内摩擦角大,三者劣化率与循环次数N之间的变化规律同样符合指数分布。在砂岩三轴压缩试验基础上,对水岩作用下岩石劣化机理进行了研究。研究成果对于受水位反复升降影响的水库边坡安全性治理具有一定参考价值。
Abstract
During the construction and operation of reservoir, the repeated rise and fall of water level in the reservoir affects the safety of bank slope. The deterioration law of the mechanics properties of rock mass of bank slope under cyclic water saturation and drying was investigated in this research via triaxial compression test of sandstone in water level fluctuation zone. The concept of deterioration rate was introduced to explore the effect of water-rock interaction on sandstone's mechanical properties. And the deterioration mechanism of sandstone under water-rock interaction was analyzed by means of scanning electron microscope. Results demonstrated that the peak compressive strength of sandstone increased with the climbing of confining pressure under the same degree of water-rock interaction; under the same confining pressure, the peak compressive strength, cohesion, and internal friction angle all decreased with the proceeding of the wet-dry cycles, and such relationship accorded with exponential distribution. When the interaction between water and rock intensified, the minimum value of the deterioration rate of peak compressive strength tended towards 31.35%; cohesion, 30.61%; and internal friction angle, 15.37%. The fluctuation of water level had great influence on peak compressive strength and cohesion of sandstone. The relations between the deterioration rates of peak compressive strength, cohesion, and internal friction angle and the cycle number N also obeyed exponential distribution. Last but not the least, the mechanism of rock deterioration under water-rock interaction is studied based on the triaxial compression test result.
关键词
砂岩 /
饱水-风干循环 /
三轴压缩试验 /
电镜扫描 /
劣化率 /
峰值抗压强度 /
黏聚力 /
内摩擦角
Key words
sandstone /
cyclic water saturation and drying /
triaxial compression test /
electron microscopy /
deterioration law /
peak compressive strength /
cohesion /
internal friction angle
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