Borehole Stress meters are designed to measure stress changes in rock and can be installed in boreholes of depth up to 35 meters.
The Borehole Stress meter of PMT consists of a highly tensioned steel wire stretched across the diameter of a stainless-steel proving ring. The proving ring is wedged tightly inside the borehole and when a stress change occurs the ring is distorted. This distortion causes change in the tension of the wire, altering its natural resonant frequency which is transmitted through a cable to the readout unit.
Introduction:
Features:
- - Accurate, robust, and low cost
- - Long term stability with high reliability
- - Suitable for large strain measurement
- - Frequency signal can be transmitted over long distance
- - Built-in thermistor for temperature measurements.
Specifications:
| Sensor type | Vibrating Wire |
| Range | 70 MPa (Hard Rock), 40MPa (Soft Rock) |
| Sensitivity | 14-70 kPa (Hard Rock), 7-60kPa (Soft Rock) |
| Borehole Depth | Up to 30m |
| Temperature Range | -20 to 80°C |