【作者】 解海军；

【导师】 孟小红；

【作者基本信息】 中国地质大学（北京） ， 地球探测与信息技术， 2009， 博士

【摘要】 近年来,老窑采空区透水成为煤矿突水的显著特点之一,给煤矿的安全生产带来极大的威胁。采空区赋存大多没有什么规律可言,其分布往往是孤立、不连续的,从而造成其探测成为一个难点。瞬变电磁法(TEM)作为积水采空区的一种探测手段,有着独特优势和显著效果。论文针对TEM探测积水采空区常见的几个关键技术进行了系统的研究,取得以下几个方面的研究成果:通过煤系地层中发育的单层积水采空区、充气高阻采空区、多层采空区等不同地电模型的数值正演计算,分析了不同条件下采空区的瞬变电磁响应和断面反映特征。对高阻围岩中的积水采空区而言,瞬变电磁法信号反映明显,而对于充气等高阻采空区,曲线上和断面上反应微弱,难以显示采空位置。瞬变电磁法探测煤矿积水采空区常用的装置为大定源-中心回线组合方式,由此产生的边框效应问题本文进行了系统的理论分析和数值模拟。计算显示,在发射框内,不同的地方其一次场差别很大,在中心处其场值最大。均匀半空间和层状地电模型的二次场分析显示,不同发射边长的垂直磁场响应,在相同偏移距下的衰减率不尽相同,在偏移距为零时,垂直磁场能量最强。在发射框的中心约1/3发射面积范围内激发场强变化较小,基本可以认为是均匀场。简要分析了瞬变电磁法探测时的干扰类型,对于噪音在曲线上的表象特征进行了分析。从小波分析理论出发,对干扰的识别和压制进行了论述,采用了Lipschitz指数α的变化特性来区分异常和非异常。通过实例的噪音压制,说明了这种压制干扰的可行性。对于地形产生的干扰,本文也进行了分析和研究,并从实践方面进行了地形校正效果分析。附加效应产生的机理很复杂,试验表明,浅层的积水采空区的附加效应对瞬变电磁信号的影响很大,不能将这种现象简单的归结为干扰,本文从理论上分析了附加效应产生的原因,实例证明将附加效应应用到积水采空区的探测中能取得理想的效果。在采用瞬变电磁法探测煤矿积水采空区的时候,要注意选取不同的工作参数。文中针对不同地质情况的采空区实例探测表明,TEM对煤矿积水采空区的探测具有良好效果。更多还原

【Abstract】 Since recent years, water penetration from gob of abondaned mines became a significant feature of water inrush in coal mines, threating serousely safe production in coal mines. There is not any regularity for occurrence of gob. The distribution of gob is often isolated and discontinous, so the detection of gob became difficult problem. Transient electromagnetic method(TEM) has special advantage and evident result as an approach for detection of water-accumulating gob. Aiming at some common key technologies in detection of water-accumulating gob by TEM with configuration of central loop—fixed loop source, the paper carried out systematic study, and obtained following results:Through forward calculation of different ground electric models of water-accumulating gob in single layer, air-filled highly resistant gob and gob in multiple layer developed in coal measures, the characteristics of transient electromagnetic response and section of gobs under different conditons were analysed. For water-accumulating gob in highly resiastant surrounding rocks, transient electromagnetic signals are evident, but air-filled highly resitant gob has weak transient electromagntic response on curves and sections, and is difficult to show its location.The transient electromagnetic installation conmmonly sued in detection of water-accumulating gob in coal mines is configuration of central loop—fixed loop sources,systematic theoric analysis and numerical modeling were made in the paper in term of rim effect. Calculation of primary field shows that in emession rim, the primary field is quite different at defferent places and has the maximum value at the center. Secondary field analysis of uniform half space and stratified ground electric model indicated response of vertical magnetic field for different emission side length, and the attenuation of vertical magnetic field is different at the same offset. When the offset is zero, the energy of vertical is the strongest. At the extent of about 1/3 of the center of emission rim, the stimulated field density varies a little, can be basically considered as uniform field. The type of disturbance during TEM detection and the attributes of noise on curves were analyzed. From the threory of wavelet analysis, identification and suppression of disturbance were discussed. The variation characteristics of Lipschitz exponentαwas used to disguinsh anomaly and non-anomaly. The examples of noise suppression showed the feasibility of the suppression. The paper also analyzed and studied the disturbance caused by topography and the result of topographic correction was analyzed from the view of practice.The mechanism of additional effect is very complicated. Experiment indicated that the additional effect of shallow water-accumulating gob had significant impact on transient electromagnetic signals. And the additional effect could not be simply incorporated into disturbance. The cause of additional effect was analyzed theorically. The examples confirmed that a the application of additional effect in detection of water-accumulating gob can produce ideal results.During detection of water-accumulating gob in coal mines by TEM, different operation parameters should be selected. The cases of detection of gob in different gerological conditions showed that as a detection approach TEM had good result for detection of water-accumulating gob in coal mines.更多还原