Deformation of buried steel pipe piles by a disaster or change over time etc. may effect the bearing strength of a structure, so it is important to correctly clarify such deformation. An attempt was made to apply an ultrasonic sidewall measuring device, the Drilling Monitor (DM-604) from KODEN. The DM-604, which is device used for pre-pile driving inspections of holes bored for foundation piles of high-rise buildings etc., confirms the inclination of boreholes. As its ultrasonic sensor is lowered and raised inside a borehole filled with water, it measures the distance from the ultrasonic sensor to the inside wall at the same time as it records this distance on electrically-sensitive recording paper, confirming the inclination of the borehole.
　With the conventional method of using an ultrasonic sidewall measuring device, it is possible to measure section deformation of a buried steel pipe pile if it is only slightly inclined, but it has been confirmed that when a buried steel pipe pile is extremely inclined, or when the pile is a batter pile, an inappropriate situation occurs: the ultrasonic sensor contacts the pipe wall as it rotates. So a new method.installing an ultrasonic sensor and gyro on a carrier and inserting it into the inside of a buried steel pipe pile.was proposed, it has been shown that it can be used to measure inclination and unevenness of the surface. The results revealed that it is necessary to understand section shapes such as those of buried steel pipe piles in greater detail, so by directly recording and analyzing signals received from an internal circuit board of the ultrasonic sidewall measurement device, more precise measurements are done, obtaining generally good results. This improvement successfully boosted the nominal precision of the DM-604 from 2% to 0.5%. And an analysis use application needed for these measurements has been manufactured, so a document will be complied concerning these.