Borehole inclination testing (BIT) measures the verticality of a borehole and its existing piles. BIT uses the auger/bucket itself as a centraliser. This results in the elimination of a heavy to move system. The BIT enables fast and accurate determination of inclination in both dry and wet boreholes. Large boreholes and diaphragm walls can be quickly tested several times during drilling. This allows for real time corrective action while drilling. When testing existing piles, a special centraliser attached to the BIT sensor and lowered into a standard access tube. Importantly, this cuts out the need for expensive inclinometer tubes. The BIT sensor includes a gyro which constantly measures and compensates the rotation of the sensor in the tube.
BIT testing is important as all piling specifications prescribe the allowable deviation of the pile axis from the vertical.
- FHWA rules, for instance, limit the pile inclination to 20 mm/m, or 2%.
- The ICE (UK) specifications allow a deviation of not more than 1:75 or 1.33%.
Similarly, these documents also set down the allowable deviation of raked piles. In diaphragm and secant walls, the specification is typically even more restrictive.
- BIT Main unit, rechargeable battery operated with wireless communication channels to the depth meter (3), the mobile computer (4) and the rig operator box (5, not seen). Rugged polyurethane cable connects the main unit to the inclination sensor (2).
- Precision bi-axial inclination sensor, harsh environment and pressure proof to 300m, attached to the auger/bucket using a simple disposable metal plate.
- Precision wireless depth meter, transmitting accurate depth to the main box.
- Any Android mobile device with Bluetooth communication, (Phone/Tablet)
- Rig operator satellite box with two LEDs: GO/Stop (Optional)
Once the borehole has been drilled to the required depth, the inclinometer is rigidly attached to the drill bit (bucket or auger) and the depth encoder hung from the rig. The bucket is then lowered (without turning) into the open hole. The descent is stopped at predetermined depths for inclination reading and the deviation calculated in real time by integrating the inclination over depth. Having reached the bottom, the procedure is repeated on the way up to the surface. The resulting error is distributed over the whole depth
A special centralizer is attached to the BIT sensor and lowered into a standard access tube through the depth encoder. The sensor is lowered by hand and the descent is stopped every few meters. reading stabilizes in a second or two and the process is repeated all the way down and back up to ground level. The resulting error is distributed over the whole depth.
- Low-cost compared to traditional caliper systems
- Quick to test (minutes per borehole)
- User friendly wizard-driven software. No training needed.
- Works on any diameter