BIT measures the verticality of a borehole AND of existing piles
All piling specifications prescribe the allowable deviation of the pile axis from the vertical.
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 System components
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.
The BIT system
BIT inclination sensor attached to a bucket