Q

Can I tell anything about the condition at the top and bottom of the shaft based on TIP results?

A

Temperature diffusion is purely radial along most of the length of the shaft. Given knowledge of the normal temperature distribution across a shaft, a nearly linear relationship between temperature and radius is observed in the vicinity of the cage. Near the ends of the shaft (top and bottom), the temperature is diffused both radially and longitudinally, making the normal temperature profile to appear rounded; this temperature "roll-off" is normal. When the temperature curve at the ends of the shaft fits a characteristic hyperbolic tangent shape, then the shaft end conforms to a cylindrical shape. If the temperature curve is not a hyperbolic tangent shape then there is an integrity concern, such as a soft bottom. Numerical algorithms can be used to correct the temperature to radius correlation on the basis of proximity to the ends of the shaft and the normal in-situ regional soil temperature. See Q 1091