碳酸盐岩孔洞模型中超声波传播特性

 以孔洞型碳酸盐岩的小岩柱为对象，采用二维超声波数值模拟与物理模型实验相结合的方法，从运动学及动力学角度，研究了多频率下超声波在不同尺寸、形状及分布的孔洞模型中的传播特性。结果表明，不连续分布的单孔洞，其尺寸变化对声波速度几乎无影响但与衰减系数呈正相关，在相同尺寸下随测试频率的增加声波速度有增加的趋势，衰减系数与频率间呈幂函数递增关系；圆形孔洞、方形孔洞对声波速度影响与孔隙度有关，孔隙度9%为临界值，低于9%时影响不敏感（可忽略），高于9%时圆形孔洞对衰减系数的影响大于正方形孔洞的影响；椭圆形孔洞的影响与其纵横比有关，纵横比大于1时，随纵横比增加衰减系数的变化幅度较小，反之则衰减系数的变化幅度较大；随孔洞分布集中度的增加，声波速度呈线性规律减小，衰减系数呈线性规律增加。

Characteristics of ultrasonic propagation in carbonate rock pore model

This paper studies the characteristics of ultrasonic propagation in a model of a small pillar of the pore-cave type carbonate rock of different size and shape and distribution and in ultrasonic multi frequency, using the numerical simulation method of two-dimensional ultrasound and physical model experiments, from the perspective of kinematics and dynamics. The results show that in the single pore-cave discontinuous distribution, the size change almost has no effect on the velocity but is correlated with the attenuation coefficient positively; in the case of the same size, with the increase of the test frequency, the velocity increases, with the attenuation coefficient and the frequency in an exponential increasing relation. The influence of the hole shape (round holes or square holes) is related with the porosity. The porosity of 9% is the critical value. When it is less than 9%, the effects can be neglected; when it is more than 9%, the influence of circular holes is greater than that of square holes on the attenuation coefficient. The influence of elliptical holes is related with the aspect ratio, when the aspect ratio is greater than 1, with the increase of the aspect ratio, the attenuation coefficient changes little, whereas the attenuation coefficient varies greatly when the aspect ratio is less than 1. With the increase of the concentration of the pore distribution, the wave velocity decreases linearly, and the attenuation coefficient increases linearly.