Table 2 Classification of risk based on indicators of evaluation of water inrush.
Evaluation indicators | Risk classification of karst inrush water evaluation indicators | ||||
|---|---|---|---|---|---|
I | II | III | IV | V | |
Rock type K11 (qualitative) | Clayey dolomite | Argillaceous limestone | Limy dolomite dolomite | Dolomitic limestone Muddy dolomite limestone | Limestone |
Rock structure K12 (qualitative) | Open-grain structure | Bright crystal structure | Granular structure | Micrite exture | Bioclastic structure |
Rock mass structure K21 (qualitative) | Block shaped | Lumpy | Laminarization | Fracture shape | Granular shape |
Strata dip angle K22/(°) | > 60° | 45 –60° | 30–45° | 15–30° | < 15° |
Rainfall infiltration coefficient K31 | < 0.1 | 0.1–0.3 | 0.3–0.4 | 0.4–0.5 | > 0.5 |
Ground slope K32/(°) | > 45° | 45–30° | 30–20° | 20–10° | < 10° |
Vertical zoning of karst water K41 (Qualitative) | Superficial karst zone | Vertical seepage zone | Seasonal variation karst zone | Shallow saturation zone | Pressure saturated zone |
Groundwater in relation to spatial location of tunnels K42/(m) | 0 –10 | 10–20 | 20–30 | 30–60 | > 60 |
