瞬变电磁法隧道超前地质预报正演模拟及应用实例

发布时间：2018-04-23 05:27

本文选题：瞬变电磁法 + 隧道超前地质预报　；参考：《广西大学》2015年硕士论文

【摘要】：瞬变电磁法(TEM)是一种时间域地球物理探测方法,其广泛应用于矿产勘探、灾害预报和工程应用等领域。在隧道施工过程中,断层、裂隙、溶洞等是常见的地质不良体,而这些不良地质体往往伴随着大量的水体,如果在隧道开挖过程中没有提前采取有效的预防措施,则可能引发突水突泥等地质灾害的发生；由于瞬变电磁法对低阻体反映灵敏,水体相对隧道围岩来说属于低阻体,将瞬变电磁法引用到隧道超前地质预报成为近年的研究热点。针对隧道不良含水构造的瞬变电磁响应特征和隧道突水突泥灾害的瞬变电磁探测与预报进行了以下三方面的研究并取得了相当的研究成果：1.采用Ansys电磁模拟软件对各种复杂的地质模型进行了二维瞬变电磁正演,在充分分析模型参数的基础上,完成了对隧道含水构造模型的构建和二维数值模拟并针对特殊构造分析了电磁响应特征,同时对瞬变电磁探测的整个反应过程进行视图再现。数值模拟的主要成果如下：通过数值模拟实验的结果可以看出,全空间和隧道空间的瞬变电磁响应差异主要集中在前期。低阻破碎带模型中瞬变电磁响应的影响主要集中在：(1)破碎带厚度越厚响应值越大；(2)破碎带距离掌子面越近响应值越大；(3)破碎带规模越大响应值越大；(4)破碎带和围岩的相对电性差异越大,其响应值相差越大。不同充实度的充水溶洞对瞬变电磁响应表现为：溶洞充实度越大,电磁响应值越明显。2.根据相似性原理,选取合适的实验材料,设计了物理模型实验,对各种低阻地质体进行模拟并分析各瞬变电磁响应。主要成果如下：隧道空间的存在对探测结果有一定的影响,这个影响主要集中在对探测信号反应值大小的影响,对探测距离与探测反应值的衰减规律和反应出的现象影响不大。针对不同位置低阻体,电磁感应衰减曲线和多测道图均显示出一定的规律。模拟了金属干扰的影响,结果显示金属干扰对探测结果影响很大,一般来说应该尽量掌子面后方存在大量的金属干扰物或者金属干扰物应该远离掌子面。3.以岑溪大隧道和岭脚隧道为依托,结合地质勘查报告和实际开挖记录,对隧道突水突泥问题进行了预报,并引入了扇形探测新方法,预报结果和实际开挖结果相符,预报结果可信。
[Abstract]:Transient electromagnetic method (TEM) is a time-domain geophysical method, which is widely used in mineral exploration, disaster prediction and engineering applications. In the course of tunnel construction, faults, fissures and caverns are common geological bodies, which are often accompanied by a large number of water bodies, if effective preventive measures are not taken in advance in the course of tunnel excavation. Because the transient electromagnetic method is sensitive to the low resistivity body and the water body belongs to the low resistivity body relative to the surrounding rock of the tunnel, the application of the transient electromagnetic method to the advanced geological prediction of the tunnel has become a hot research topic in recent years. In this paper, the transient electromagnetic response characteristics of poor water-bearing structures in tunnels and the transient electromagnetic detection and prediction of tunnel water inrush and mud inrush disasters are studied in the following three aspects and a considerable research result: 1 is obtained. The 2-D transient electromagnetic forward modeling of various complex geological models is carried out by using Ansys electromagnetic simulation software. Based on the full analysis of the model parameters, The construction of tunnel water structure model and two-dimensional numerical simulation are completed, and the electromagnetic response characteristics are analyzed for the special structure, and the whole reaction process of transient electromagnetic detection is reproduced in view at the same time. The main results of numerical simulation are as follows: the results of numerical simulation show that the difference of transient electromagnetic response between the whole space and the tunnel space is mainly concentrated in the early stage. The effect of transient electromagnetic response in the low resistivity fracture zone model is mainly concentrated in: 1) the thicker the thickness of the broken zone, the larger the response value. (2) the larger the response value of the broken zone is to the palm surface, the larger the response value is. (the larger the scale of the broken zone is, the larger the response value is, the larger the response value is, the larger the response value is, the larger the response value is, the larger the response value is. The greater the difference in relative electrical properties of rocks, The larger the response value is, the greater the difference is. The transient electromagnetic response of water-filled caverns with different degree of enrichment is as follows: the larger the enrichment degree of the cavern, the more obvious the electromagnetic response value is. 2. According to the principle of similarity, the physical model experiments are designed to simulate and analyze the transient electromagnetic responses of various low-resistivity geological bodies by selecting suitable experimental materials. The main results are as follows: the existence of tunnel space has a certain influence on the detection results, which mainly focuses on the magnitude of the response value of the detection signal, but has little effect on the attenuation law of the detection range and the detection response value and the phenomenon of the response. For low resistive bodies at different positions, both the electromagnetic induction attenuation curve and the multi-track diagram show certain laws. The effect of metal interference is simulated. The results show that metal interference has great influence on the detection results. Generally speaking, there should be a large number of metal disturbances behind the face of the palm or metal interference should be far away from the face of the palm. 3. Based on the Cenxi big tunnel and Lingjiao tunnel, combined with the geological exploration report and the actual excavation record, the water inrush and mud inrush of the tunnel are forecasted, and a new method of sector detection is introduced. The prediction results are consistent with the actual excavation results. The forecast results are credible.
【学位授予单位】：广西大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：U452.11;P631.325

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