RocFall 5.0
Statistical Analysis of Rockfalls
Collision Analysis Verification Manual
© 2007-2013 Rocscience Inc.
Table of Contents
RocFall Collision Verification Problems
1
Comparison between Lump Mass and Rigid Body Formulations ............................... 1
2
West Rifle Test Site ..................................................................................................... 5
3
Glenwood Canyon Example ........................................................................................ 7
1
1.1
Comparison between Lump Mass and Rigid Body Formulations
Problem Description
In this problem, the output using lump mass or rigid body formulations are compared against
each other. Rocfall 4.0 uses the lump mass formulation, which assumes rocks as point masses.
Rocfall 5.0 has an additional engine using rigid body mechanics, which incorporates shape into
impact calculations. In this study, a very small radius is used for a spherical rock to eliminate any
shape effects when comparing results. Angular velocity is not considered.
Three cases are used in the analysis:
Case 1:
Seeder Properties
Initial Location
(X0, Y0) = (0, 0)
Initial Velocity
Vx = 3.5 m/s
Vy = 0 m/s
Rock Properties
Mass: 10 kg
Density: 2.1x106kg/m3
Case 2:
Seeder Properties
Initial Location
(X0, Y0) = (0, 10)
Initial Velocity
Vx = 2 m/s
Vy = 0 m/s
Rock Properties
Mass: 10 kg
Density: 2.1x106kg/m3
Lump Mass Parameters
Normal Restitution
Tangential Restitution
Dynamic Friction
Slope Roughness
= 0.7
=1
=0
=0
Rigid Body Parameters
Normal Restitution
Dynamic Friction
Rolling Friction
= 0.7
=0
=0
Lump Mass Parameters
Normal Restitution
Tangential Restitution
Dynamic Friction
Slope Roughness
= 0.7
=1
=0
=0
Slope Coordinates
X
0
3.05
6.71
9.75
13.41
20
22
22.199
Y
0
-12.19
-12.19
-24.38
-24.99
-24.99
-24.99
-24.99
Slope Coordinates
X
0
25
Y
0
0
Rigid Body Parameters
Normal Restitution
Dynamic Friction
Rolling Friction
= 0.7
=0
=0
1
Case 3:
Seeder Properties
Initial Location
(X0, Y0) = (0, 5)
Initial Velocity
Vx = 6 m/s
Vy = 0 m/s
Rock Properties
Mass: 10 kg
Density: 2.1x106kg/m3
1.2
Lump Mass Parameters
Normal Restitution
Tangential Restitution
Dynamic Friction
Slope Roughness
= 0.7
=1
=0
=0
Slope Coordinates
X
0
10
20
32
Y
0
0
-2.68
-2.68
Rigid Body Parameters
Normal Restitution
= 0.7
Dynamic
Friction
=0
Rigid Body
Parameters
Rolling Friction
=0
Results
Bounce Height (m)
Figure 1-1 to Figure 1-6 presents the bounce height and total kinetic energy graphs for Case 1, 2
and 3. The results using the lump mass formulation compare well with the rigid body
formulation. They are almost identical.
20
18
16
14
12
10
8
6
4
2
0
Lump Mass
Rigid Body
0
5
10
15
Location (m)
20
25
Figure 1-1: Bounce height for Case 1
2
Total Kinetic Energy (J)
2000
1800
1600
1400
1200
1000
800
600
400
200
0
Lump Mass
Rigid Body
0
5
10
15
Location (m)
20
25
Figure 1-2: Total kinetic energy for Case 1
Bounce Height (m)
12
10
Lump Mass
8
Rigid Body
6
4
2
0
0
5
10
15
Location (m)
20
25
Figure 1-3: Bounce height for Case 2
Total Kinetic Energy (J)
1200
Lump Mass
1000
Rigid Body
800
600
400
200
0
0
5
10
15
Location (m)
20
25
Figure 1-4: Total kinetic energy for Case 2
3
Bounce Height (m)
6
5
Lump Mass
4
Rigid Body
3
2
1
0
0
5
10
15
Location (m)
20
25
30
Figure 1-5: Bounce height for Case 3
Total Kinetic Energy (J)
800
700
Lump Mass
600
Rigid Body
500
400
300
200
100
0
0
5
10
15
Location (m)
20
25
30
Figure 1-6: Total kinetic energy for Case 3
1.3
Input files
V001 - Comparing Formulations - Case 1 (Lump Mass).fal5
V001 - Comparing Formulations - Case 1 (Rigid Body).fal5
V001 - Comparing Formulations - Case 2 (Lump Mass).fal5
V001 - Comparing Formulations - Case 2 (Rigid Body).fal5
V001 - Comparing Formulations - Case 3 (Lump Mass).fal5
V001 - Comparing Formulations - Case 3 (Rigid Body).fal5
4
2
2.1
West Rifle Test Site
Problem description
This problem verifies the average bounce height and translational velocity using the results from
the Colorado Rockfall Simulation Program (CRSP) [1]. CRSP calibrated its simulation using
data collected from a 300 feet high hillside near Rifle, Colorado. The slope material consists of
thin desert soil with rocky ledges and sparse vegetation. 5000 spherical rocks are used in the
analysis using the lump mass formulation. The slope model and material properties are presented
in Figure 2-1 and Table 2-1.
Initial Location
X0 = 1.32 ft
Y0 = 325 to 330 ft
Initial Velocity
Vx = 1 ft/s
Vy = -1 ft/s
Rock Properties
Radius: 2.2 ft
Mass: 7358 lb
Cell #1
2 3
4
5
6
8
7
9 10
11
12
13
Figure 2-1: Slope model
Table 2-1 Slope material properties
1
Normal
Coefficient of
Restitution
0.25
Tangential
Coefficient of
Restitution
0.82
2
0.32
3
Dynamic
Friction
Surface
Roughness (°)
Beginning
X, Y
Ending
X, Y
0
5.15
0, 320
8, 314
0.84
0
20
8, 314
18, 304
0.32
0.84
0
15
18, 304
34, 290
4
0.32
0.84
0
25
34, 290
66, 258
5
0.30
0.84
0
15
66, 258
92, 240
6
0.30
0.84
0
9.99
92, 240
120, 214
7
0.30
0.83
0
9.99
120, 214
199, 164
8
0.33
0.82
0
12.22
199, 164
260, 140
9
0.33
0.82
0
9.99
260, 140
269, 138
10
0.34
0.84
0
16.23
269, 133
305, 110
11
0.34
0.84
0
14.31
305, 108
335, 90
12
0.34
0.84
0
9.99
335, 87
396, 51
13
0.34
0.85
0
5.15
396, 51
410, 49
Cell #
5
2.2
Results
The average bounce height and translational velocity are presented in Figure 2-2 and Figure 2-3.
The results obtained from Rocfall compare well with the CRSP model.
Maximum Bounce Height
(ft)
16
Rocfall
CRSP
14
12
10
8
6
4
2
0
0
50
100
150
200
250
300
Horizontal Location (ft)
350
400
450
Figure 2-2: Average bounce height for horizontal locations along the slope
Maximum Translational
Velocity (ft/s)
100
Rocfall
CRSP
80
60
40
20
0
0
50
100
150
200
250
300
Horizontal Location (ft)
350
400
450
Figure 2-3: Average translational velocity for horizontal locations along the slope
2.3
References
1.
Pfeiffer, T.J. (1989). Rockfall Hazard Analysis Using Computer Simulation of Rockfalls.
(Doctoral Dissertation). Colorado School of Mines, Golden, Colorado.
2.4
Input files
V002 - West Rifle Slope (Lump Mass).fal5
6
3
3.1
Glenwood Canyon Example
Problem Description
This problem verifies the average bounce height and translational velocity using the results from
the Colorado Rockfall Simulation Program (CRSP) [1]. CRSP calibrated its simulation using
data collected from quartzite cliffs 750 feet above Interstate 70 (I-70) in Glenwood Canyon,
Colorado. The study was for the design of rockfall mitigation after rockfall incidents damaged
two retaining walls under construction. The upper third of the slope is granitic bedrock with
sparse vegetation and a thin soil cover, while the other two thirds above I-70 is talus cover with
scattered shrubs. 5000 spherical rocks are used in the analysis using the lump mass formulation.
The slope model and material properties are presented in Figure 3-1 and Table 3-1.
Initial Location
X0 = 0 ft
Y0 = 800 to 810 ft
Initial Velocity
Vx = 1 ft/s
Vy = -1 ft/s
Rock Properties
Radius: 2.2 ft
Mass: 3761 lb
Retaining Wall
I-70
Cell #1
2
3
4
5
6
7
8
9 10 11 12
14 15
13
Figure 3-1: Slope model
7
Table 3-1 Slope material properties
1
Normal
Coefficient of
Restitution
0.35
Tangential
Coefficient of
Restitution
0.85
2
0.35
0.85
3
0.35
4
Dynamic
Friction
Surface
Roughness (°)
Beginning
X, Y
Ending
X, Y
0.60
0.65
25
0, 794
224, 620
25
224, 620
248, 610
0.85
0.65
25
248, 600
306, 540
0.32
0.81
0.65
10
306, 530
385, 480
5
0.32
0.81
0.40
20
385, 480
500, 390
6
0.32
0.81
0.40
18
500, 390
557, 360
7
0.31
0.80
0.40
25
557, 360
848, 157
8
0.31
0.80
0.50
10
848, 157
925, 110
Cell #
9
0.31
0.82
0.65
0
925, 110
933, 110
10
0.32
0.80
0.65
0
933, 95
968, 80
11
0.40
0.90
0.65
0
968, 78
1002, 78
12
0.32
0.80
0.65
0
1002, 60
1069, 25
13
0.32
0.82
0.65
0
1069, 25
1075, 27
14
0.40
0.90
0.65
0
1075, 27
1104, 27
15
0.32
0.82
0.65
0
1104, 27
1153, 4
3.2
Results
The average bounce height and translational velocity are presented in Figure 3-2 and Figure 3-3.
The results obtained from Rocfall compare well with the CRSP model.
Maximum Bounce Height
(ft)
40
Rocfall
CRSP
35
30
25
20
15
10
5
0
0
200
400
600
800
Horizontal Location (ft)
1000
1200
Figure 3-2: Average bounce height for locations along the slope
8
Maximum Translational
Velocity (ft/s)
90
80
70
60
50
40
30
20
10
0
Rocfall
CRSP
0
200
400
600
800
Horizontal Location (ft)
1000
1200
Figure 3-3: Average translational velocity for locations along the slope
3.3
Input Files
V003 - Glenwood Canyon Example (Lump Mass).fal5
3.4
References
1.
Pfeiffer, T.J. (1989). Rockfall Hazard Analysis Using Computer Simulation of Rockfalls.
(Doctoral Dissertation). Colorado School of Mines, Golden, Colorado.
9

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