Abstract: This paper presents low stress integrity test experience on large diameter long bored concrete piles supporting railroad bridges. Two frequently encountered issues are discussed: shallow deflect and weak reflection from the bottom of piles. To resolve these problems, different citation methods could be used for the integrity tests. The results indicate that appropriate high and low frequency stress waves used in the test can effectively overcome these issues.

Key words: Large Diameter Long bored pile, Low Stress Test, Shallow Defects, Pile Bottom Reflections