Table 1 Comparison of the measured depth and the calculated gap depth
From: An impact echo method to detect cavities between railway track slabs and soil foundation
No | Cavity Size (mm) | TCL Thickness (mm) | Calculation Gap depth (mm) | Frequency (Hz) |
|---|---|---|---|---|
1 | 400 × 400 | 250 | 259 | 2035 |
2 | 252 | 2087 | ||
3 | 246 | 2144 | ||
4 | 199 | 2658 |