BIT

Borehole Inclination Tester

Overview

BIT measures the verticality of a borehole AND of existing piles

Borehole

BIT uses the auger/bucket itself as the centralizer. Eliminating the need for 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 may be quickly tested several times during drilling to enable real-time corrective action.

Existing piles:

A special centralizer is attached to the BIT sensor and lowered into a standard access tube (No need for an expensive inclinometer tube). The BIT sensor includes a gyro which constantly measures and compensates the rotation of the sensor in the tube.

Background

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.

The BIT is compliant with the ASTM D8232-18 Standard

Piletest BIT borehole inclination test system

The BIT system

System components

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). A 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)

BIT System components

Operation for boreholes

Once the borehole has been drilled to the required depth, the inclinometer is rigidly attached to the drill bit ((2)bucket or auger), and the depth encoder is hung from the rig (3). The bucket is then lowered (without drilling) into the open hole, pulling the BIT cable (1). The descent is stopped at predetermined depths for inclination reading, and the deviation is calculated (4) 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 to improve accuracy.

Operation for existing piles

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. The reading stabilizes in a second or two, and the process is repeated continuously until reaching the bottom. Then the same procedure is done on the way up to ground level. The resulting error is distributed over the whole depth.

Advantages:

Low-cost compared to traditional caliper systems
Quick to test (minutes per borehole)
User-friendly wizard-driven software. No training is needed. (Give it a try on your phone)
Works on any diameter