A New Reliability Rock Mass Classification Method Based on Least Squares Support Vector Machine Optimized by Bacterial Foraging Optimization Algorithm

Table 3

Subclassification criteria of rock mass around tunnels.

Rock classification	I	II	III1	III2	IV1	IV2	IV3	V1	V2
BQ interval	≥551	550 ∼ 451	450 ∼ 401	400 ∼ 351	350 ∼ 316	315 ∼ 285	284 ∼ 251	250 ∼ 211	210 ∼ 150