Knowledge Base

Figure 1 gives a visual representation of the orientation of the B0, A180 and B180 in relation to the A0 direction. Also shown is the +/- direction in relation to the data being plot in the Inclinometer related software In-Profile

Fig 1. Inclinometer A and B Directions

In relation to one another, the A and B directions of a borehole are always the same (that is, B0 is always 90° clockwise from A0 and so on). However, when installing a casing you have the task of defining which of the keyways you want to act as the A0 direction. This choice often depends on the circumstances and objectives of a particular installation, but the generally accepted rule is that A0 points towards the expected direction of movement.

For example; if you were monitoring a hillside, and the purpose of this was to see if any ground is slipping down the hill, you would be expecting the direction of movement to be directly down the slope of the hill, and so you would install the casing to have one keyway pointing directly down the slope and be defined the A0 direction.