Tang Fujian, Yang Jianzhou, Li Hong-Nan, Liu Fuqiang, Wang Ningbo, Jia Peng, Chen Yizheng
State Key Laboratory of Coastal and Offshore Engineering, School of Civil Engineering, Dalian University of Technology, Dalian 116024, China.
Henan Tianchi Pumped Storage Energy Corporation, Nanyang 474664, China.
Materials (Basel). 2018 Aug 23;11(9):1511. doi: 10.3390/ma11091511.
In this article, a magnetic sensor is proposed to monitor borehole deviation during tunnel excavation. It is made by piling four super-strong N42 NdFeB cylinder magnets and then encasing them in an aluminum alloy hollow cylinder. The distribution of the magnetic field produced by the magnetic sensor and its summation with the geomagnetic field (GMF) in a global coordinate system are derived based on the theory of magnetic fields. An algorithm is developed to localize the position of the magnetic sensor. The effect of the GMF variation on the effective monitoring range of the magnetic sensor is also studied numerically. Field validation tests are conducted at Jinzhai Pumped-Storage hydroelectric power station, during the excavation of an inclined tunnel in Anhui Province of China. Test results show that the algorithm and the magnetic sensor are used successfully to detect the deviation of the borehole with an estimated error of approximately 0.5 m. The errors are mainly from the measurement errors of the coordinates, of both the test and the measurement points. The effective monitoring range of the magnetic sensor is dependent on the direction of the magnetic sensor as well as the variation of the GMF.
本文提出了一种用于监测隧道开挖过程中钻孔偏差的磁传感器。它是通过将四个超强的N42钕铁硼圆柱形磁体堆叠起来，然后将它们封装在一个铝合金空心圆柱体中制成的。基于磁场理论，推导了磁传感器产生的磁场在全局坐标系中的分布及其与地磁场（GMF）的叠加。开发了一种算法来定位磁传感器的位置。还通过数值研究了地磁场变化对磁传感器有效监测范围的影响。在中国安徽省金寨抽水蓄能电站的一条倾斜隧道开挖过程中进行了现场验证试验。试验结果表明，该算法和磁传感器成功地用于检测钻孔偏差，估计误差约为0.5 m。误差主要来自测试点和测量点坐标的测量误差。磁传感器的有效监测范围取决于磁传感器的方向以及地磁场的变化。
