Water Inrush Risk Assessment Based on AHP and Advance Forecast Approach: A Case Study in the Micangshan Tunnel

Table 11

Risk grade system evaluation of the water inrush disaster index.

First-grade evaluation index	Second-grade evaluation index	Quantitative value of disaster causing factors
U1	C1	No fissure hard rock	Mudstone, sandstone, shale	Argillaceous siltstone, sandy mudstone, shale	Dolomite, argillaceous limestone, and other soluble rocks	Dolomitic limestone, dolomite,
	Score	0–4	4–8	8–12	12–16	16–20
	C2	I, II	III	IV	V	VI
	Score	0–4	4–8	8–12	12–16	16–20
	C3 (cm)	Thick layer	Middle-thick layer	Middle layer	Thin layer	Unconsolidated layers
	Score	0–8	8–12	12–15	15–18	18–20
U2	C4	Convex type	Flat type	Single slope type	Parallel type below the side of the valley	Parallel type below the valley
	Score	0–8	8–12	8–12	15–18	18–20
	C5	Convex type	Flat type	Mixed type	Depression type	River crossing type
	Score	0–6	6–10	10–14	14–17	17–20
U3	C6 (m)	＜1.5	1.5–3	3–5 or contact surfaces of different rock	5–8	＞8
	Score	0–6	6–10	10–14	14–17	17–20
	C7	Other parts of fold structure	Wing of the gently dipping fold structure	Wing of the steep fold structure	Core of the gently dipping fold structure	Core of the steep fold structure
	Score	0–3	3–6	6–10	10–15	15–20
U4	C8 (m)	＜200	200–500	500–1000	1000–1500	＞1500
	Score	0–2	2–6	6–14	14–16	16–20
	C9 (m)	＜100	100–300	300–500	500–700	＞700
	Score	14–20	10–14	6–10	4–6	0–4
U5	C10	No water inrush	Water inrush in water-bearing crack	Water inrush in fault fracture zone	Water inrush in karst pipeline	Water inrush in karst cave
	Score	0–4	4–12	12–16	16–18	18–20
	C11	Bedrock fissure water	Clastic rock fissure water	Clastic rock fissure water, bedrock fissure water	Karst fissure water, clastic rock fissure water	Karst fissure water, clastic rock fissure water, bedrock fissure water
	Score	0–6	6–10	10–14	14–17	17–20
	C12	Dry	Humid	Dripping	Rainy	Downpour, local inrush water
	Score	0–2	2–8	8–12	12–16	16–20