孔隙环境特征对高岭土超声波波速影响机理研究

Influence mechanism of pore environment characteristics on ultrasonic wave velocity of kaolin

高岭土是工程中常见的黏性土体,其微观结构对孔隙环境的变化十分敏感。目前针对高岭土孔隙环境特征与声波波速关系的研究还有待深入。基于超声波测试理论,采用RSM-SY6超声波检测仪,研究了不同孔隙环境条件下,高岭土超声波波速的变化规律,并从黏土颗粒的排列方式及其与孔隙溶液的相互作用等微观角度,分析了孔隙环境特征对高岭土超声波波速的影响机理,为超声波检测技术在土体中的应用提供了一定的理论依据。结果表明:(1)孔隙比越大,高岭土超声波波速越低;(2)随着含水率的增加,高岭土超声波波速先小幅度降低,后大幅度升高;(3)孔隙溶液酸碱度对高岭土超声波波速的影响与边缘等电pH值有关,当孔隙溶液pH值等于边缘等电pH值时,超声波波速最大;(4)盐分的加入使高岭土超声波波速降低,当盐溶液浓度在0~0.5 mol/L时,波速下降最快。相同阴离子条件下,高价阳离子对超声波波速的降低作用更明显。研究结果可为黏性土体声学特性研究提供参考,同时也为超声波检测技术在土体中的应用提供了一定的理论依据。

Kaolin is a common clay in engineering.The microstructure of kaolin is very sensitive to the change of pore environment.At present,the research on the relationship between pore environment characteristics and acoustic wave velocity of kaolin remains to be further studied.In this paper,based on the ultrasonic test theory,RSM-SY6 ultrasonic detector is used to study the change rule of ultrasonic wave velocity of kaolin under different pore environment conditions.In addition,the influence mechanism of pore environment characteristics on ultrasonic wave velocity of kaolin is analyzed from the microscopic perspective of the arrangement mode of clay particles and the interaction between clay particles and pore solution.The results show that(1)the ultrasonic wave velocity of kaolin decreases with the increasing void ratio.(2)With the increasing water content,the ultrasonic wave velocity of kaolin decreases slightly at first and then increases greatly.(3)The effect of pore solution pH value on ultrasonic wave velocity of kaolin is related to the edge isoelectric pH value.When the pore solution pH value is equal to the edge isoelectric pH value,the ultrasonic wave velocity is the maximum.(4)The addition of salt reduces the ultrasonic wave velocity of kaolin.When the concentration of saline solution ranges from 0 to 0.5 mol/L,the wave velocity decreases rapidly.Under the same anion condition,the high valence cation has a more obvious effect on the reduction of ultrasonic wave velocity.This paper provides a reference for the study of the acoustic characteristics of viscous soil,and also provides a theoretical basis for the application of ultrasonic detection technology in soil.