干湿循环作用下砂岩三轴压缩力学特性试验研究

Experimental study on mechanical properties of sandstone under triaxial compression under wet and dry cycles

自三峡大坝修建完成,随着每年的蓄水泄洪,在库区范围内形成了大量消落带边坡。蓄水-泄洪如此反复作用,使得消落带岩石长期遭受干湿循环的作用,岩石自身产生了劣化,导致消落带边坡出现滑坡或存在崩塌的潜在危险,从而威胁库区航道的安全运营。针对不同干湿循环次数(0次、30次、60次、90次)作用后的砂岩试件进行超声波检测、单三轴压缩等试验,分析了波速、质量和峰值强度等基本力学参数与干湿循环次数之间的关系。结果表明:随着干湿循环的次数增大,砂岩试件的波速、质量均减小,在循环次数30次~60次时减小幅度最明显。峰值强度与干湿循环次数存在多项式关系,也是随着干湿循环的次数增大而减小。

Since the completion of the construction of the Three Gorges Dam,with the annual water storage and discharge,a large number of water-level slopes have been formed in the reservoir area.The repeated action of water storage and flood discharge makes the rocks in the riparian zone suffer from the dry-wet cycle for a long time,and the rocks themselves are degraded,which leads to the potential danger of slope landslide or collapse in the riparian zone,thus threatening the safe operation of the waterway in the reservoir area.The relationship between the wave velocity,mass and peak strength and the number of dry and wet cycles was analyzed by ultrasonic testing and uniaxial compression tests on sandstone specimens treated with different dry and wet cycles(0,30,60,90).The results show that the wave velocity and mass of sandstone specimens decrease with the increase of the number of wet-dry cycles,and the decrease amplitude is most obvious when the number of cycles is 30~60.There is a polynomial relationship between the peak intensity and the number of wet-dry cycles,which also decreases with the increase of the number of wet-dry cycles.