GT-20 Tunnel addresses tunnel construction safety needs. By emitting a pulsed magnetic field through a small loop and receiving the secondary-field signal, it performs high-sensitivity detection of low-resistivity anomalies ahead of the face, such as water-bearing structures, fracture zones, and karst caves. The equipment is lightweight and flexible with a small detection blind zone, and can be rapidly and densely deployed at the face, providing a real-time geological early-warning basis for tunnel excavation.
High-power solution with small coils in tunnels: trading current for signal-to-noise ratio, pulling out the weak anomalies ahead of the face.
Advance detection for tunnels, roadways, shafts, and adits; water-bearing faults, fissure water, karst, and karst caves within 150 m ahead of and around the face.
Construction can still proceed with large iron objects, supports, and drilling rigs not removed, and under conditions of standing water or inrush water requiring pumping.
Geophysical data is submitted within half a working day after fieldwork ends; combined with geological conditions it predicts water-rich zones and guides borehole verification.
| Parameter | Receiver Module | Parameter | Transmitter Module |
|---|---|---|---|
| A/D Converter | 32-bit | Transmitter Voltage (V) | 36-57 |
| Dynamic Range | 160dB | Transmitter Current (A) | ≥150 |
| Sampling Rate | 1μs、4μs、16μs | Current Pulse Width (ms) | 10、20、40 |
| Number of Acquisition Channels | 2 | Transmitted Waveform | Bipolar square wave with a 1:1 duty cycle |
| Background Noise | 1μV | Maximum Transmitter Power (kW) | 8.5 |
| Voltage Measurement Range | -200V-200V | Synchronization Method | Cable synchronization |
| Voltage Measurement Resolution | ≤300nV | Turn-off Time | 0.5–300 μs, depending on the supply current and transmitter coil |
| Measurement Accuracy | 0.001 | Computer System | Windows-based operating interface |
| Input Gain Range | 1/80-8000 | Data Interface | USB2.0 |
| Minimum Sampling Interval | 4μs | Storage Capacity | ≥30,000 measurement points |
| Noise Suppression | >100dB | Dimensions (L × W × H) | 403mm×330mm×178mm |
| Frequency Bandwidth | 0-500kHz | Weight | 8kg |
| Stacking Times | 1~200 | Operating Temperature | -10℃-50℃ |
| Parameter Category | GT-20 |
|---|---|
| System Positioning | TEM system for advance geological forecasting in tunnels and roadways |
| Standard Transmitter Loop Specification | Compact 0.85 m × 0.85 m square loop designed for tunnel applications |
| Standard Receiver Probe / Coil | Separate receiver coil designed for operating conditions involving compact tunnel loops |
| Common Survey Configuration | Compact central-loop configuration |
| Compatible Transmitter Current | Standard configuration supports transmitter currents of ≥150 A |
| Typical Applications | Water-bearing zone detection ahead of tunnels and roadways, and underground surveys (maximum detection depth: ≥150 m) |
| Design Features | Integrated, lightweight coil configuration suited to confined roadway and tunnel spaces |
The standard kit is designed for field transport and routine survey setup. Actual contents may vary by model and order configuration.
Integrated Transmitter-Receiver Unit × 1
Industrial Tablet PC × 1
Ground TEM Probe × 1
Ground TEM Probe Connection Cable × 1
Transmitter Loop × 1
Integrated Advance Detection Coil × 1
Advance Detection Coil Connection Cable × 1
| Name | Model | Material Code |
|---|---|---|
| GT-20 Standard Ki | GT-20 Kit | M0.0010 |
| Transient Electromagnetic Instrument | GT-20 | M0.2002 |
| Industrial Tablet PC (including Network Cable) | ONERugged | M6.0001 |
| Integrated Transmitting and Receiving Coil for Advance Detection | T-20 | M4.2003 |
| Advance Detection Coil Connection Cable | T-21 | M6.0015 |
| Processing Software (including USB Dongle) | TEM Processing Software | M5.1010 |
| TEM Backpack Harness | Dual-Shoulder | M6.0006 |
| Ground TEM Probe | T-10 | M4.2001 |
| Transmitter Loop | 6mm²*40m | M4.2002 |
| Ground TEM Probe Connection Cable | T-11 | M6.0014 |
| TEM Charger | CDQ-5 | M4.1005 |
| Tablet PC Charger | CDQ-6 | M4.1006 |
