煤岩界面弱反射波小波多分辨分析

WAVELET MULTI-RESOLUTION ANALYSIS OF WEAK REFLECTED WAVE FROM THE INTERFACES OF COAL SEAM AND STRATA

煤层厚度探测,特别是放顶煤开采时顶煤厚度快速、准确地探测对掌握放煤力度、保证煤质以及准确计算回收率具有重要意义。声波反射法是目前顶煤厚度探测的有效方法之一。弱反射波信号识别是声波法煤层厚度探测中的一个关键问题。针对这一问题,对顶煤厚度探测信号进行了小波多分辨分析;提出了从小波的紧支性、连续性和高阶消失矩3个方面选择小波基对信号进行分解的原则;应用Db4小波对实测信号进行了4层多尺度分解,分析了煤层夹矸和煤层顶板反射波在不同尺度下的时频特征,提高了煤岩界面弱反射波的识别能力和煤层厚度探测的精度。

High-speed and accurate detecting of the thickness of the top coal seam plays an important role in the caving method. It is very significant for mastering accurately caving dynamics, guarantying the coal quality and computing exactly the recovery ratio. The elastic wave reflection method is one of the effective methods of detecting the thickness of the top coal seam. To identify the signal of the weak reflected wave is a key problem to detect the thickness of the coal seam by using elastic wave. So, the detecting signals of thickness of the coal seam are processed by means of the wavelet multi-resolution analysis. The principle to choose the wavelet base for decomposing the signals is put forward according to the properties of its compact support, continuity and high-order vanishing moment. The actual detecting signals are decomposed using Db4 wavelet and the properties of their time-frequency are analyzed. Therefore, the ability to identify the weak reflected wave and the accuracy to detect the thickness of the coal seam are considerably imoroved.