A GEOTECHNICAL INVESTIGATION OF THE 2013 FATAL ROCKFALL

IN ROCKVILLE, UTAH

Carl J. JacklitchAbdul Shakoor

Location

What happened? A large rockfall occurred on December

12, 2013. Approximately 2700 tons of rock fell. Property damage included the house,

garage, and car. 2 fatalities resulted.

Rockfall History

Site Selection

Rockville Bench Supplemental Data

Roadside Supplemental Data

Radio Tower Supplemental Data

Supplemental Sites

Stratigraphy

Stratigraphy

Shinarump Member

Upper Red Member

Shnabkaib Member

Mapping of Discontinuiti

es Includes:

• Orientation• Presence of Water• Roughness• Spacing• Infilling Material• Continuity• Aperture

Laboratory Methods Friction Angle

Dry Density

Resistance to Weathering

Determination of Friction Angle

Test showed • 39° for Upper Red member• 46° for Shinarump member

Actual value used • 35° for Upper Red member• 42° for Shinarump member

Determination of the Rocks Resistance to Weathering

Data Analysis Determine principal joint sets

Kinematic analysis

Rockfall rollout distance

Determination of Principal Joint SetsShinarump member

1. 84, 196 2. 87, 158 3. 87, 229 4. 04, 086

1 2

3

4

Determination of Principal Joint SetsUpper Red member

Moenkopi Principal Joint Sets

1

3

2 1. 84, 228 2. 88, 314 3. 02, 074

Kinematic Analysis Planar Failures

Shinarump member

Joint 1

Joint 2

Joint 3

Bedding

Average Slope Face

Critical Pole

Kinematic Analysis Wedge Failures

Shinarump member

Joint 1

Joint 2

Joint 3

Bedding

Average Slope Face

Critical Intersections

Kinematic Analysis Toppling Failures

Shinarump memberJoint 1

Joint 2

Joint 3

Bedding

Average Slope Face

Critical Pole

Evidence in the Field for Wedge, Planar and Toppling Failures

Largest block that was intact at the fatal site (520 tons) Distance farthest block traveled : 661 feet

House LocationRoad LocationShinarump memberMoenkopi Fm.

Largest block that was intact at the fatal site (520 tons) Distance farthest block traveled : 661 feet

House LocationRoad LocationShinarump memberMoenkopi Fm.

Farthest traveled block (50 tons).Block dimensions: super ellipse 4 (2:3).

Distance traveled of farthest block: 830 feet

Farthest traveled block (50 tons).Block dimensions: super ellipse 4 (2:3).

Distance traveled of farthest block: 830 feet

Other Factors to Consider

2013 Precip. (in) EventsNov high avg low high avg low high avg low high avg low high avg low high avg high sum17 59 46 33 37 35 29 91 67 39 30.19 30.09 29.94 10 10 10 8 2 - 018 63 49 35 37 29 25 79 48 26 30.26 30.17 30.12 10 10 10 12 5 18 019 59 44 30 42 34 28 96 71 47 30.14 30.03 29.97 10 10 10 13 4 16 020 51 40 28 45 38 28 100 87 66 30 29.94 29.89 10 10 1 7 2 - 0.03 Rain21 53 47 41 46 44 41 100 91 68 30.07 29.97 29.92 10 9 2 12 5 17 0.39 Rain , Thunderstorm22 45 43 41 43 38 35 98 80 71 30.1 30.04 29.95 10 9 2 36 15 52 0.36 Rain23 45 42 38 38 37 36 97 82 70 30.15 30.09 30.03 10 9 2 34 19 47 0.26 Rain24 49 40 30 40 36 30 100 88 58 30.22 30.16 30.13 10 9 1 13 3 16 0.01 Rain25 54 39 24 35 30 23 99 81 37 30.37 30.27 30.21 10 10 2 10 2 - 026 59 42 25 35 28 24 97 64 28 30.43 30.36 30.31 10 10 10 16 4 23 027 55 46 36 33 31 28 72 57 43 30.33 30.22 30.13 10 10 7 17 7 22 028 55 44 33 34 31 27 92 62 35 30.25 30.17 30.13 10 10 10 15 8 21 029 56 42 28 35 32 27 99 79 37 30.34 30.29 30.24 10 10 10 9 4 - 030 53 38 23 36 30 22 99 84 51 30.36 30.32 30.26 10 10 7 12 2 - 0

2013 Precip. (in) EventsDec high avg low high avg low high avg low high avg low high avg low high avg high sum

1 52 36 21 34 29 20 99 83 45 30.43 30.35 30.31 10 10 0 8 2 - 0 Fog2 62 42 22 36 29 21 99 75 29 30.32 30.11 29.88 10 10 10 12 3 - 03 57 40 24 33 28 24 99 67 29 29.88 29.66 29.48 10 10 0 22 5 31 0 Snow4 30 20 9 29 16 4 99 74 43 29.99 29.83 29.56 10 8 1 18 11 26 0 Snow5 29 14 -2 12 5 -5 90 73 39 30.05 29.97 29.93 10 10 10 10 3 - 06 34 18 1 19 9 -1 89 71 31 30.15 30.07 30.03 10 10 10 7 3 - 0.027 32 28 23 32 25 17 100 85 69 30.03 29.84 29.71 10 6 0 22 7 34 0 Snow8 27 8 -12 19 3 -16 89 76 51 30.15 30.05 29.89 10 10 10 15 6 20 0.039 25 3 -19 12 -5 -24 88 77 53 30.48 30.35 30.15 10 10 10 8 3 - 0

10 34 14 -6 21 4 -11 91 76 49 30.48 30.35 30.25 10 10 10 9 3 - 011 43 20 -3 23 10 -8 89 63 37 30.42 30.36 30.3 10 10 10 16 3 23 0.0712 50 33 16 27 18 11 96 60 30 30.42 30.3 30.2 10 10 10 16 4 23 013 45 28 11 24 18 10 95 72 40 30.31 30.19 30.12 10 10 10 13 3 16 0

Wind (mph)Temp. (°F) Dew Point (°F) Humidity (%) Sea Level Press. (in) Visibility (mi)

Wind (mph)Temp. (°F) Dew Point (°F) Humidity (%) Sea Level Press. (in) Visibility (mi)

Freeze-Thaw and Ice-wedging

Many gullies act as channels for debris

to flow.

What Areas are Most Hazardous?

Hazard Map

High HazardModerate HazardLow Hazard

High HazardModerate HazardLow HazardCurrent Hazard Boundary

Hazard Map

Possible Mitigation Measures

Rock bolts/anchors Chain mesh on the slope Shotcrete weak units

Always with drains Benches and riprap Move the homes Ditches/Catchments Retaining Walls

Acknowledgments Advisor and Committee

Dr. Abdul Shakoor Dr. Daniel Holm Dr. David Hacker

Utah Geological Survey Bill Lund Tyler Knudsen

Funding Kent State University School of Hard Rocks Scholarship Kent State Student Chapter of SGE Research Scholarship Kent State Student Chapter of AEG Research Scholarship

Special Thanks Mayor Tracy Dutson Robin Dutson Jenny Jasiekiewicz Even Cerveny

Questions?