煤样吸水全过程纵波波速变化规律及波形特征实验研究

发布时间：2018-05-18 14:54

本文选题：采矿工程 + 煤样　；参考：《岩石力学与工程学报》2017年08期

【摘要】：为了研究含水煤体的纵波波速变化规律及波形特征,开展原煤试样吸水全过程的纵波测试实验;研究煤体纵波波速与孔隙率、含水饱和度之间的变化规律;基于FFT和HHT研究不同含水饱和度煤样波形幅频和时频特征。结果表明:煤体纵波波速同时受孔隙率和含水饱和度的影响;波速随含水饱和度的增加总体呈现非线性增加趋势,当含水饱和度达到70%左右时,波速增加速率明显提高;水自身性质及煤体内部孔隙水均匀存在形式是导致含水煤波速增加的主要原因。纵波波速随孔隙率的增加总体呈现线性降低趋势,含水饱和度越高波速受孔隙率影响越小,表明水的存在降低了煤体孔隙率对波速的影响。煤样在吸水过程中的波形频率分布存在显著性差异,波形主频随含水饱和度的增加呈现向低频非线性移动的"频移"现象;含水饱和度越大、孔隙率越大,波形最大幅值越小。Hilbert三维能量谱能够反应波形的频带能量分布及随时间的变化特征;随着煤样含水饱和度的增加,波形高频成分所占比例逐渐降低,且高能量频带范围不断向低频移动,表明煤体中孔隙水不但加快了波形中所有频带能量的衰减速度,而且对高频信号的吸收损耗大于低频信号。
[Abstract]:In order to study the variation law and characteristics of P-wave velocity of water-bearing coal, the experiment of P-wave measurement of the whole process of water absorption of raw coal sample is carried out, and the variation law of P-wave velocity, porosity and water saturation of coal body is studied. The amplitude-frequency and time-frequency characteristics of coal samples with different water saturation were studied based on FFT and HHT. The results show that the longitudinal wave velocity of coal body is affected by both porosity and water saturation, and the wave velocity increases nonlinear with the increase of water saturation. When the water saturation reaches about 70%, the increase rate of wave velocity increases obviously. The main reasons for the increase of the wave velocity of water-bearing coal are the properties of water itself and the uniform existence of pore water in coal body. The wave velocity of the longitudinal wave decreases linearly with the increase of porosity, and the higher the water saturation is, the less the influence of the wave velocity is on the porosity, which indicates that the existence of water reduces the influence of coal porosity on the wave velocity. In the process of water absorption, there are significant differences in the wave frequency distribution of coal samples. The main wave frequency moves to the low frequency nonlinearity with the increase of water saturation, and the higher the water saturation is, the larger the porosity is. The smaller the maximum value of the waveform is. Hilbert three-dimensional energy spectrum can reflect the frequency band energy distribution of the waveform and its variation with time, and with the increase of the water saturation of coal sample, the proportion of high frequency components of the waveform decreases gradually. And the high energy band range is moving to the low frequency band, which indicates that the pore water in the coal body not only accelerates the attenuation speed of all the frequency band energy in the waveform, but also absorbs the high frequency signal more than the low frequency signal.
【作者单位】：中国矿业大学煤炭资源与安全开采国家重点实验室;中国矿业大学矿业工程学院;中国矿业大学安全工程学院;
【基金】：国家自然科学基金资助项目(51504250) 江苏省自然科学基金资助项目(BK20150183) 中国矿业大学煤炭资源与安全开采国家重点实验室自主研究课题(SKLCRSM14X03)~~
【分类号】：TD821

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