【作者】 梁爽；

【导师】 李貅；

【作者基本信息】 长安大学 ， 地球探测与信息技术， 2008， 硕士

【摘要】 瞬变电磁法(Transient Electromagnetic Method)简称TEM,属于感应类电磁探测方法。该方法具有简便、快捷、对低阻体敏感等优点,广泛的应用于矿产资源勘探、环境地质调查、水文地质与工程地质调查等领域,已成为煤矿水害探测最为有效的方法,为矿井安全生产提供了有力的保证。本文侧重于实际应用,对瞬变电磁法探测煤矿水害的机理、数值模拟计算、资料处理解释方法等方面进行探讨研究。从麦克斯韦方程出发,对目前普遍应用的TEM同心装置,推导了水平层状介质下的瞬变响应表达式;简要介绍了几种常用的反演解释方法;针对煤矿归纳了影响瞬变电磁法资料所涉及的几种主要干扰类型,针对各类噪声的特点分析了50Hz工频电噪声及高值噪声的抑制方法。探讨了煤矿开采区勘探时非涡流直接引起的瞬变响应的识别与抑制方法、地形影响校正方法、金属构件影响校正方法等;由于瞬变电磁法正反演理论都是建立在垂直阶跃电流激发条件下的,而实际激发电流不能立即关断,要有一定延迟,其波形不是方波,所以要进行校正。基于此,推导了关断电流斜坡情况下的响应表达式,给出了简便的校正方法;介绍了有限单元法求解二、三维瞬变电磁响应的基本理论,综合一般煤矿地电特征,并根据煤矿开采的特点简化设计典型水害地电模型,进行正演计算。结果表明,对于积水采空区和直立导水断层等水害源,电阻率断面图和多测道曲线异常表现明显,但低阻异常从浅层到深层贯通,有拖长现象。实际应用印证了正演模拟的结论,同时取得了良好的地质效果和社会效益,为煤矿安全高效生产提供了有力保证。更多还原

【Abstract】 As one kind of time-domain electromagnetic prospecting method, the transient electromagnetic method (shorted as TEM) has been applied widely with it’s advantage such as facility, express & sensitive on low-resistance in prospecting resource ,surveying and investigating hydrology, engineering and environment. It is the best choice of detecting water hazards in coal mine areas and has been become powerful resolution to ensure safety in coal mine producing.The paper aims at main aspects of central-loop TEM, such as the theory of detecting water hazards, modeling, data processing etc.Basically on Maxwell equation, induced solution of TEM response of horizontal layered medium using central loop unit widely applied in TEM prospecting. Introduced briefly on several most commonly method on inversion and interpretation. Summed up the main kinds of noises, analyzed the methods of canceling 50Hz AC as well as high amplitude noise according to their features in TEM data. Discussed the identification and suppression methods of the transient response that caused by the non-swirl, the methods of terrain correction, the methods of metal structures correction in mining area exploration. Because the forward & inversion theory of TEM is founded on vertical current pulse, the stimulation current turn off has ramp actually. So must be correct, and a simple correction is given. Introduced the basic theory of Solving two or three-dimensional TEM response by the finite element method (FEM). After considered the characteristics of electricity of earth and mining situations in coal mine, designed simplify model, and do forward calculations. The calculation results showed that resistivity sections and more measured performance curve maps obviously abnormal to reflect the actual situation of the water hazards in the mined-out area and mine water fault, but very low resistivity from shallow to deep link up, with prolonged phenomenon.Practical applications are also confirms the conclusions of this calculations, made a good geological effects and social benefits at the same time. The applications provided a strong guarantee for the efficient production of coal mine safety.更多还原