It is difficult to inspect the soundness of underground walls using a pile integrity test (PIT) because the elastic wave caused by the input at the wall head spreads throughout plane of the wall. This paper describes a reasonable method for evaluating the soundness of underground walls using a PIT. By applying a low-pass filter to the reflected wave observed at the wall head, the wave components reflected from the wall ends and cracks can be separated from the components reflected from the wall sides. This allows the wave to be clarified for soundness evaluation.
