Journal of Geological Research / 2014 / Article / Tab 9

Research Article

Assessment of Slope Instability and Risk Analysis of Road Cut Slopes in Lashotor Pass, Iran

Table 9

Rockfall hazard rating system parameters and their scores [35].

Category Rating criteria and score
Points 3 Points 9 Points 27 Points 81

Slope height7.5 m15 m22.5 m30 m

Ditch effectivenessGood catchmentModerate catchmentLimited catchmentNo catchment

Average vehicle risk (% of time)25%50%75%100%

Percent of decision sight
distance
Adequate sight distance, 100% of low design valueModerate sight distance, 80% of low design valueLimited sight distance, 60% of low design valueVery limited sight distance, 40% of low design value

Roadway width included paved shoulders13.20 m10.80 m8.40 m6.00 m

Geologic character
 Case 1
  Structural conditionDiscontinuous joints, favorable orientationDiscontinuous joints, random orientationDiscontinuous joints, adverse orientationContinuous joints, adverse orientation
  Rock frictionRough, irregularUndulatingPlanarClay infilling or slickenside
 Case 2
  Structural conditionFew differential erosion featuresOccasional differential erosion featuresMany differential erosion featuresMajor differential erosion features
  Difference in erosion ratesSmallModerateLargeExtreme

Block size30.48 cm60.96 cm91.44 cm121.92 cm

Volume of rockfall per event 2.3 m34.6 m36.9 m39.2 m3

Climate and presence of water
on slope
Low to moderate precipitation, no freezing periods, no water on slopeModerate precipitation or short freezing periods intermittent water on slopeHigh precipitation or long freezing periods or continual water on slopeHigh precipitation and long freezing periods or continual water on slope and long freezing periods

Rockfall historyFew fallsOccasional fallsMany fallsConstant falls