Combined System of Magnetic Resonance Sounding and Time-Domain Electromagnetic Method for Water-Induced Disaster Detection in Tunnels

Abstract

Underground construction projects such as tunnel construction are at high risk of water-induced disasters. Because this type of disaster poses a serious threat to worker safety and productivity, instruments and methods that can accurately detect the water source are critical. In this study, a water detection instrument that combines Magnetic Resonance Sounding (MRS) and Time-domain Electromagnetic Method (TEM) techniques to yield a joint MRS-TEM interpretation method was developed for narrow underground spaces such as tunnels. Joint modules including a transmitter and receiver were developed based on a dual-purpose and modular design concept to minimize the size and weight of the instrument and consequently facilitate transportation and measurement. Additionally, wireless control and communication technology was implemented to enable inter-module cooperation and simplify instrument wiring, and wireless synchronization was accomplished by implementing a Global Positioning System (GPS)-based timing scheme. The effectiveness and reliability of the instrument were verified via indoor laboratory tests and field measurement signal tests. Furthermore, the practicability of the combined instrument and its interpretation method was verified via a field case performed in a tunnel in Hubei, China.

Random Noise Suppression of Magnetic Resonance Sounding Data with Intensive Sampling Sparse Reconstruction and Kernel Regression Estimation

“…The blue lines display the spectra of the time-series of the sampling frequency f prop , and the red lines display the spectra of the time-series of rectangular sparse reconstruction by different sampling frequencies that correspond to the left-hand column. 12 Figure 5. Figure 5.…”

“…So far, the MRS method and instrument have been further researched and developed in many countries such as France, the United States, Germany, China and other countries [6][7][8]. The MRS method has been applied to hydrological investigation, observation of permafrost thaw, monitoring the cavity in glacier, water-induced disaster 2 of 32 detection, and infiltrating water surveys [9][10][11][12][13]. However, when the MRS instrument is exploited for groundwater exploration, the received signal is particularly weak and easily degraded in ambient electromagnetic interference [14].…”

Feasibility of Tunnel TEM Advanced Prediction: A 3D Forward Modeling Study

“…The TEM method has shown its advantage at sites where space is highly limited since the transmission of pulse-type electromagnetic signals does not require a highpower device. The above aspects prompt applying the TEM method in tunnel advanced detection, and it has thrived over the past two decades [13][14][15][16]. However, most of these interpretation results were carried out through empirical relationships between the buried depth of the geologic body and the arrival time of the electromagnetic wave.…”