Sonic Reflection (Pulse–Echo) Measurements

NDT frequently uses sonic reflection (pulse-echo) measurements to determine the length of sheet, wood, pipe and concrete piles and the quality or integrity of drill shafts and caissons. Sonic reflection measurements determine the time required for a stress wave generated with a projectile impact or hammer impact to travel from the top to the bottom of the pile or shaft and be reflected back to the top. Using the travel time and a wave velocity, as measured on exposed sections of the pile, the length of the pile can be calculated.