声发射的频域特性可以反映在时域参数中难以分析的岩石结构和应力条件等问题。研究浸泡时间对泥质矿物岩石力学性质及声发射频域特征的影响,对于全面分析水岩耦合条件下的岩石变化具有重要意义。在这项研究中,在干燥条件下对含蒙脱石的砂岩进行了单轴压缩试验和声发射试验,饱和,和不同的浸泡时间条件,重点分析了浸没时间对岩石声发射主频的影响。结果表明,浸泡时间对抗压强度有不同程度的影响,主要声发射频率的分布特征,主频的频率范围,砂岩失稳破坏的前兆信息。初始饱和后,岩石样品的强度从干燥状态下的53.52MPa下降到49.51MPa,浸泡30天后稳定下来.干燥和最初饱和的岩石样品均显示出三个主频带。经过不同的浸泡日,主频带出现在95kHz和110kHz之间。浸泡5天后,0kHz附近的主频带逐渐消失。浸泡60天后,35kHz至40kHz之间的主频带逐渐消失,随着浸泡时间的增加,声发射信号的主频增加。在干岩石样品的加载过程中,声发射信号的主频主要集中在0kHz到310kHz之间,饱和后,主频率均低于180kHz。干岩样破裂前最显著的特征是高频频繁发生和主频突变。在破裂之前,初始饱和和浸入样品5、10和30天的前兆事件的特征是主频率突然变化的出现和快速增加,以及主频率的频率范围的扩大。浸泡60天后,岩样破裂的前兆特征逐渐消失,主频率的突然变化经常发生在样品加载的不同阶段,这使得很难根据这些突然的变化准确预测标本的破裂。
The frequency domain characteristics of acoustic emission can reflect issues such as rock structure and stress conditions that are difficult to analyze in time domain parameters. Studying the influence of immersion time on the mechanical properties and acoustic emission frequency domain characteristics of muddy mineral rocks is of great significance for comprehensively analyzing rock changes under water-rock coupling conditions. In this study, uniaxial compression tests and acoustic emission tests were conducted on sandstones containing montmorillonite under dry, saturated, and different immersion time conditions, with a focus on analyzing the effect of immersion time on the dominant frequency of rock acoustic emission. The results indicated that immersion time had varying degrees of influence on compressive strength, the distribution characteristics of dominant acoustic emission frequencies, the frequency range of dominant frequencies, and precursor information of instability failure for sandstones. After initial saturation, the strength of the rock sample decreased from 53.52 MPa in the dry state to 49.51 MPa, and it stabilized after 30 days of immersion. Both dry and initially saturated rock samples exhibited three dominant frequency bands. After different immersion days, a dominant frequency band appeared between 95 kHz and 110 kHz. After 5 days of immersion, the dominant frequency band near 0 kHz gradually disappeared. After 60 days of immersion, the dominant frequency band between 35 kHz and 40 kHz gradually disappeared, and with increasing immersion time, the dominant frequency of the acoustic emission signals increased. During the loading process of dry rock samples, the dominant frequency of acoustic emission signals was mainly concentrated between 0 kHz and 310 kHz, while after saturation, the dominant frequencies were all below 180 kHz. The most significant feature before the rupture of dry rock samples was the frequent occurrence of high frequencies and sudden changes in dominant frequencies. Before rupture, the characteristics of precursor events for initially saturated and immersed samples for 5, 10, and 30 days were the appearance and rapid increase in sudden changes in dominant frequencies, as well as an enlargement of the frequency range of dominant frequencies. After 60 days of immersion, the precursor characteristics of rock sample rupture gradually disappeared, and sudden changes in dominant frequencies frequently occurred at various stages of sample loading, making it difficult to accurately predict the rupture of specimens based on these sudden changes.