An iterative inversion method using transient electromagnetic data to predict water-filled caves during the excavation of a tunnel
An iterative inversion method using transient electromagnetic data to predict water-filled caves during the excavation of a tunnel
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DOI：
10.1190/geo2018-0253.1
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发表时间：
2019-03
期刊：
影响因子：
3.3
通讯作者：
Yan Li;Taiyue Qi;B. Lei;Zongyang Li;Wangping Qian
中科院分区：
文献类型：
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作者：
Yan Li;Taiyue Qi;B. Lei;Zongyang Li;Wangping Qian
全空间瞬变电磁资料的正确解释一直是隧道开挖工程中的一个关键安全问题。针对狭窄隧道条件下充水溶洞的解释问题，提出了一种基于三维时域有限差分（FDTD）正演计算和方向算法的迭代反演方法。共对125组三维FDTD正演计算结果进行了分析，以确定响应数据与洞穴几何条件之间的相关性。基于相关性建立了方向算法，提高了迭代反演的收敛速度。利用提出的迭代反演方法，成功地反演了掌子面前方充水溶洞的位置和体积。通过迭代程序，对隧道条件下充水溶洞探测的模拟反演结果进行了准确分析，相对误差小于10%。迭代反演方法在明月山隧道工程中的应用表明，该方法能够解释充水洞穴的尺寸，并且适用于只有单个测量点的狭窄隧道掌子面。所提出的迭代反演方法可以单独使用或与其他检测技术相结合，从而为工程师提供了一个更好的预警系统，检测隧道中的充水洞穴。
The correct interpretation of full-space transient electromagnetic data has always constituted a critical safety problem during tunnel excavation projects. Targeting the interpretation of water-filled caves under narrow tunnel conditions, we have developed an iterative inversion method based on 3D finite-difference time-domain (FDTD) forward calculations and a direction algorithm. In total, 125 groups of 3D FDTD forward calculation results are analyzed to identify the correlations between the response data and the geometric conditions of the cave. A direction algorithm is established based on the correlations, thereby increasing the iterative inversion convergence speed. Using the proposed iterative inversion method, the location and volume of the water-filled cave in front of the tunnel face are successfully inverted. Through an iterative program, the inversion results of simulations involving the detection of water-filled caves under tunnel conditions are accurately analyzed, and the relative error is less than 10%. The application of the iterative inversion method to the Mingyue Mountain Tunnel project suggests that this method is capable of interpreting the size of water-filled caves and it is valid for a narrow tunnel face with only a single available measurement point. The proposed iterative inversion method can be used alone or in combination with other detection techniques, thereby providing engineers with a better early warning system for detecting water-filled caves in tunnels.