The caliper log tools used to measure the diameter of the pile shaft. The application can be applied to a different field, not only pile foundation. Clipper logging test will provide the diameter of pile shaft related to depth. The measurement is essential to verify the cross-section of the pile shaft. The drilled shaft size will vary.
In some cases, size is less than required. On the other hand oval shape may form in many pile shafts due to differential pressure in the crust.