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利用螺旋CT机和智能超声波测速仪对5种尺寸的砂岩试样进行干燥及不同饱和条件下的无损检测试验。试验结果表明,当试件直径一定时(D=50 mm),真空饱和法吸水率比自然浸水法略大,饱和吸水率与试件高度几乎成线性相关,试件两个方向的尺寸比值为2.0附近时其吸水能力较强,高径比最大的h/D=3.5时其吸水能力最差;由于岩石天然缺陷造成的各向异性,试件尺寸选取越小其各向异性指数越高,尺寸足够大其宏观均匀性才明显;砂岩的宏观力学参数和细观特征都存在尺度效应,当试件高径比h/D<2.0时岩样的弹性模量波动比较大,当高径比h/D≥2.0时试件计算弹性模量随着高度的增加而缓慢增加。得到了不同含水率砂岩无损检测参数的尺度效应方程,公式表明砂岩的吸水效果与试件的纵波波速的平方和CT数反比例相关,对于研究水岩相互作用时考虑试件的尺度效应有一定的指导意义。
Five kinds of sandstone samples were dried and tested under different saturation conditions by using spiral CT and intelligent ultrasonic anemometer. The results show that when the diameter of the specimen is constant (D = 50 mm), the water absorption of the vacuum saturation method is slightly larger than that of the natural water immersion method, and the saturated water absorption is almost linearly related to the height of the specimen. 2.0, the water absorption capacity is the highest, and the water absorption capacity is the worst when h / D = 3.5 with the maximum height-diameter ratio. The anisotropy caused by the natural defects of rock, the smaller the size of the specimen is, the higher the anisotropy index is. The macroscopic uniformity is obvious when the size is large enough. The macro-mechanical parameters and the meso-characteristics of the sandstone all have the scale effect. When the height-diameter ratio h / D <2.0, the elastic modulus of the rock specimen fluctuates relatively. When h / D≥2.0, the elastic modulus of the specimen increases slowly with the increase of height. The scale effect equation for non-destructive testing of sandstone with different water content is obtained. The formula shows that the water absorption effect of sandstone is inversely proportional to the square of the longitudinal wave velocity CT and the CT number of the sample, and the scale effect is considered when studying the interaction between water and rock Guiding significance.