Table 1 The classification standard of ultrasonic velocity ratio and weathering grade [34]
Ultrasonic Velocity ratio | Grade | Weathering extent |
|---|---|---|
0–0.2 | 6 | Residual soil |
0.2–0.4 | 5 | Fully weathered |
0.4–0.6 | 4 | Highly weathered |
0.6–0.8 | 3 | Moderately weathered |
0.8–0.9 | 2 | Weakly weathered |
0.9–1 | 1 | Unweathered |