Table 4 Classification criteria for V1-V4 grades of influencing factors in mining area division.
Dimension | V1 (Excellent) | V2 (Good) | V3 (Fair) | V4 (Poor) |
|---|---|---|---|---|
Geology | Thick, nearly horizontal coal seam; small dip and gentle strike variation; very low fault and joint density; no significant fault zones | Medium-thickness coal seam; near-horizontal to gently inclined; limited strike variation; a few faults and joints not forming large structural zones | Variable seam thickness; moderate dip; obvious strike variation; multiple small–medium faults and joints affecting local continuity | Thin or strongly split seams; steep dip; highly irregular strike; high density of faults and joints; well-developed crushed zones significantly affecting mining continuity |
Rock mass | High rock strength (high c–φ); thick and massive strata; slightly fractured; good overall integrity | Relatively high strength; medium bed thickness; fractures moderately developed; overall integrity still acceptable | Medium strength; thin–medium bed thickness; fractures obviously developed; local weak and fractured zones | Low strength or strongly weathered rock; thinly bedded; highly developed fractures and joints; crushed zones widely distributed |
Hydrogeology | Groundwater buried deep; small aquifer thickness and permeability; small inflow; very low water inrush risk and easy drainage | Moderately deep water table; limited aquifer thickness; moderate permeability and inflow; water hazard controllable with routine drainage | Relatively shallow water table; multiple aquifers with medium to high permeability; large local inflow; water hazards require targeted drainage design | Very shallow water table; thick, highly permeable aquifers; large inflow; strong hydraulic connection between aquifers; high water inrush risk and difficult drainage |
Topography | Gentle terrain; small slope angle and relief; simple and regular benches; favourable for stable pit slopes and dump layout | Gently to moderately inclined slopes; moderate relief; benches relatively regular with minor adjustments | Steeper slopes; large local relief; relatively complex stepped landform; many slope control and reshaping measures required | Steep slopes and strong relief; deeply incised gullies; complex benches; severe constraints on pit slope stability and dump layout |
Engineering | Short average haul distance; sufficient and centrally located dump capacity; good haul roads with gentle gradient and high construction standard | Moderate haul distance; dump capacity basically sufficient; haul roads generally good with some sections requiring improvement | Long haul distance for part of the route or tortuous alignment; dump capacity close to the limit during peak periods; roads with bottlenecks or steep sections; complex transportation organization | Long and tortuous haulage routes; insufficient and scattered dump capacity; poor road conditions (steep gradients, sharp curves, low standard); low transportation efficiency |
Economic | Low stripping ratio; high coal quality (high calorific value, low ash); favourable market conditions; very high economic benefit | Moderate stripping ratio; coal quality above average; normal market conditions; good overall economic return | Relatively high stripping ratio; medium coal quality; market conditions with large fluctuations; acceptable but less stable economic benefit | High stripping ratio; poor coal quality (low calorific value, high ash or many impurities); unfavourable or highly volatile market conditions; low and unstable economic benefit |
Environmental | Land mainly unused or low-sensitivity grassland/shrubland; far from ecological red lines and residential areas; few sensitive receptors to noise and dust | Land dominated by general cultivated land or ordinary woodland; moderate ecological sensitivity; few nearby sensitive receptors controllable by conventional measures | Land including a higher proportion of cultivated land or woodland; higher ecological sensitivity; several nearby noise/dust sensitive receptors; need strengthened environmental protection and reclamation measures | Land including basic farmland, important ecological protection zones or nature reserves; adjacent to many highly sensitive receptors such as dense residential areas, schools and hospitals; very strong constraints on mining and reclamation |
Social | Small land acquisition scale; sparse population; few infrastructures affected; limited legal and policy constraints; high social acceptance | Moderate land acquisition; small–medium villages or scattered settlements; general infrastructure; regulatory constraints and social resistance manageable through coordination | Large-scale land acquisition; multiple villages and many infrastructures affected; complex compensation negotiations and social coordination; stricter regulatory requirements | Very large-scale resettlement; densely populated towns or villages and important infrastructures (highways, railways, trunk pipelines, etc.) affected; strict legal and policy restrictions; high social risk |
