Application of an Improved Cloud Model and Distance Discrimination to Evaluate Slope Stability

Table 2

Single-factor slope stability evaluation index.

Rating factor	Ranking grade
	I	II	III	IV	V
Geological factors (P1)
Deformation modulus () (GPa)	33.0-50.0	20.0-33.0	6.0-20.0	1.3-6.0	0-1.3
Integrity index ()	0.75-1	0.55-0.75	0.35-0.55	0.15-0.35	0-0.15
RQD ()	90-100	75-90	50-75	25-50	0-25
UCS () (MPa)	>250	100–250	50–100	25–50	0–25
Initial geo-stress () (MPa)	0–2	2–8	8–14	14–20	20–25
Discontinuities ()
Cohesion () (MPa)	0.22-0.32	0.12–0.22	0.08–0.12	0.05-0.08	0–0.05
Friction angle () (°)	37–45	29–37	21–29	13–21	0–13
Volumetric count ()	0–3	3–10	10–20	20–35	>35
Integrity description ()	Very good	Good	Moderate	Bad	Very bad
Distance between the dip direction of the discontinuity and cutting face ()	Very far	Far	Fair	Close	Very close
Engineering factors (P2)
Slope height () (m)	0-30	30-45	45-60	60-80	80-100
Slope angle () (°)	0-20	20-35	35-45	45-60	60-80
Reinforcements ()	Surplus	Sufficient	Fair	Insufficient	Barely
Drainage condition ()	Very favourable	Favourable	Fair	Unfavourable	Very unfavourable
Excavation method ()	No excavation	Manual	Mixed	Explosion	Large explosion
Excavation intensity and volume ()	Very favourable	Favourable	Fair	Unfavourable	Very unfavourable
Environmental factors (P3)
Mean annual precipitation () (mm)	0–600	600–800	800–1,100	1,100–1,500	1,500–2,000
Saturated water content of the slope () (%)	0–20	20–40	40–55	55–75	75–100
Rainfall duration and intensity ()	Very favourable	Favourable	Fair	Unfavourable	Very unfavourable
Water table ()	Very low	Low	Fair	High	Very high
Daily maximum rainfall () (mm)	0–25	25–50	50–70	70–100	100–150
Seismic acceleration () (g)	0-0.05	0.05-0.1	0.1-0.15	0.15-0.20	0.20-0.40
Catchment area ()	Very favourable	Favourable	Fair	Unfavourable	Very unfavourable
Vegetation type ()	Very favourable	Favourable	Fair	Unfavourable	Very unfavourable
Monitoring factors (P4)
Surface deformation rate () (mm/m)	0-2	2-3	3-5	5-8	8-10
Pre-stressed anchorage force () (%)	0-8	8-15	15-20	20-25	25-30
Internal deformation rate () (mm/m)	0-0.3	0.3-0.8	0.8-1.5	1.5-2	2-3
Route inspection of slope condition ()	Very good	Good	Moderate	Bad	Very bad