COMPARISON OF ORE PASS COMPUTER SIMULATIONS FOR DESIGNS AGAINST 

DYNAMIC LOAD 

S. Iverson 

Spokane Research Laboratory, National Institute for Occupational Safety and Health, Spokane, WA 

S.J. Jung and K. Biswas 

University of Idaho, Moscow, ID 

ABSTRACT 

 Computer modeling of rock flow in ore passes is 

being investigated and compared using MSC Software’s Working Model 2D1

 (WM2D) and Itasca 

Corp.’s Particle Flow Code in Two Dimensions 

(PFC2D). This work is being carried out by the 

Spokane Research Laboratory of the National Institute 

for Occupational Safety and Health to determine the 

usefulness of computer modeling to improve ore pass 

design. The types of tests included pendulum tests to 

validate WM2D simulations and simulated single-rock 

drop tests in both WM2D and PFC2D to understand 

their contact models. Simulated rock impacts at the 

ore pass chute and the use of inclined ore passes and 

doglegs were investigated in both programs. A PFC2D 

simulation showed that dynamic loads at the chute 

gate were reduced significantly when a dogleg transition was used, and simulations in which the ore pass 

was inclined showed significant reductions in chute 

impact loads compared to simulations of a vertical ore 

pass. A released hang-up was simulated using PFC2D. 

INTRODUCTION 

 Ore passes are a common means of moving ore 

and waste downward in underground mines, as well as 

at some surface mines where under-ground haulage 

methods are used. However, the hazards related to the 

operation of ore and waste rock passes have been 

identified as a significant safety problem in the United 

States. Dynamic loads induced by falling masses of 

ore and the spontaneous collapse of hang-ups can 

cause structural failure of control gates, chutes, and ore 

pass walls with consequent threats to personnel safety. 

 

1

The mention of specific products and manufacturers does 

not imply endorsement by the National Institute for 

Occupational Safety and Health.

The purpose of this paper is evaluate the usefulness of 

computer modeling in improving ore pass design and 

thereby reduce the threat of structural damage and 

improve miner safety. 

 Gravity-induced rock flow is a simple process, but 

can pose design challenges if damage from rock 

impacts and abrasions are to be prevented. Understanding rock trajectories during a dump cycle, the 

degree of ore pass inclination, and the effects of rock 

impacts on the ore pass structure are important for 

extending the life of an ore pass. That is, an ore pass 

designed to decrease rock impact loads can save on 

repair costs or prevent hidden structural damage that 

could result in a catastrophic failure. MSC Software’s 

Working Model 2D (WM2D) and Itasca Corp.’s 

Particle Flow Code in Two Dimensions (PFC2D) 

computer programs were studied to better understand 

material flow by addressing rock particle interaction in 

an ore pass and impact forces at the ore pass bottom 

end structure. 

 In an ore pass, rock is likely to be fractured into 

smaller pieces when it strikes a surface or is struck by 

another rock. The surfaces of structural steel plates 

used in an ore pass chute can deform elastically, but 

may also deform plastically when struck. Although 

rock will break down in an ore pass, it will also 

deform elastically when struck (see Pariseau 1998). In 

double-pendulum tests, Larson et al. (1998) demonstrated that deformation of rock spheres 38 mm (1.5 

in) in diameter was nearly perfectly elastic during 

collisions. 

 The authors envisioned three important scenarios. 

• A single falling boulder within a mix of large rock 

and fines dumped at the top end of an ore pass or a 

large boulder that has broken free from the ore pass 

walls striking the walls or the bottom end structure. 
• A stream of rock striking the bottom end of an ore 

pass. In this scenario, flow rate becomes important. 

The rate of dumping into the ore pass, how the rock 

interacts with a grizzly, and the dispersion of the rock 

material as it falls down the ore pass will affect the 

impact stream at the bottom end. 

• A large mass of material released instantaneously 

and falling onto the bottom end structure. This type of

event may follow after a hang-up is blasted or another 

method of hang-up release is employed. The mass of 

rock released may strike the bottom end with a force

greater than a single boulder or a stream of rock. The 

air compressed during the fall of this mass of rock can 

cause air blast damage as well. 

 Single-particle impacts were modeled using 

WM2D, while all three scenarios were investigated 

using PFC2D. 

WM2D 

WM2D employs an impulse-based collision model 

in which the coefficient of restitution e is used to

control the elasticity of the collisions. Collisions occur 

in discrete time, and the forces arising from the

collision are affected by the time step. WM2D

calculates collision force f1 acting on mass m1 using 

the formula f1 = m1 ((v1’- v1)/∆t), where v1’ = velocity 

before collision, v1 = velocity after collision, and ∆t =

animation time step. 

When two bodies collide, there is a moment when 

the forces oppose the collision. If graphed over time,

the force of a real particle during the impact period

may be a bell-shaped curve. The force calculated by

WM2D using the integration time step is a constant if 

Figure 1.⎯Data from WM2D single-particle drop-test 

simulation 

Table 1.⎯Results of WM2D single-particle drop 

test 

Height, m Dynamic loading 

kN lb-force 

0 30.81 6,927 

10 422.90 95,080 

15 517.60 116,400 

20 598.00 132,000 

25 668.40 150,300 

30 732.60 164,700 

35 790.90 177,800 

40 845.80 190,200 

45 896.60 201,600 

50 945.20 212,500 

graphed over a given time period. According to

WM2D literature, “When the contact force between 

two bodies is measured, WM2D reports the impulse of

the collision divided by the animation time step.” 

Drop Test Simulation

Simulating collisions between particles is the key 

to creating an accurate simulation of an ore pass for 

studying material flow. As two particles collide, they

lose energy if the collision is not perfectly elastic. The 

elasticity of particles in WM2D is controlled by the 

coefficient of restitution input. Simple drop test 

simulations were conducted using a circular disk and a

horizontal wall. A 1-m- (3-ft) in diameter disk with a 

mass of 3,142 kg (6,927 lb-mass) and e of 0.2 was 

simulated and dropped from different heights to 

compare dynamic loads on the wall. e was assigned for 

each object. When a collision occurred, the smaller of 

the two e values was used to calculate the collision. In

this case, the wall was assigned the same density and

elasticity as the rock. Table 1 and figure 1 show the

increase in dynamic loads for increasing drop heights. 

Physical Model Pendulum Test

A physical model pendulum test was used to 

determine e for rock. A metal plate and a rock slab 

were used as objects onto which rock specimens were

dropped five times to get the best estimate possible 

Using a background marked off in 1-1/2-in increments, we were able to estimate the different heights 

the rocks "bounced." Figure 2 shows the results of the 

physical pendulum tests. e varied greatly, depending

on the rock specimen. We concluded that even if rock 

appeared to be the same, but came from different 
0

0.2

0.4

0.6

0.8

1

1.2

e

(rock) e 0.6 0.3 0.3 0.2 0.3

(metal) e 1 0.7 0.7 0.6 0.7

Granite Sandstone

Quartzite 

(1) Basalt Quartzite 

(2)

Figure 2.⎯Coefficient of restitution as determined from pendulum test of rock against 

steel and rock

localities, e values were very different. e was found to

be dependant on impact velocity, mass, and shape of 

the colliding bodies. 

 

Ore Pass Simulations

In WM2D, disks can be used to represent rock 

particles. However, we used particles created in odd 

shapes to best reproduce the closest simulation of rock

flow possible. Particles can be viewed flowing down

the ore pass during the simulation. When first 

dumped, they spread out, resulting in different velocity

profiles. Initial potential energies are slowed because 

of friction values assigned to the particles and the ore 

pass walls. The flow profile of the particles being 

dumped into the ore pass can be seen in the sequential 

representations created in figure 3. 

Figure 3.⎯WM2D simulations of flow in ore pass. Left: 

Particles just entering an inclined ore pass; middle: particles 

after being dumped into ore pass; right: particles have fallen

a certain distance. 

Various ore pass inclinations were simulated, and 

the impact force on the bottom end was measured for a

single particle. Figure 4 compares impact force for a

90° (vertical) ore pass to other inclinations simulated. 

These ratios show that a force reduction of up to 60% 

occurs when a 60° inclination is used. Stream impact

and hang-up release loads were not attempted in 

WM2D. 

0

0.2

0.4

0.6

0.8

1

1.2

50 60 70 80 90

Inclination (degrees)

Dyn

amic load

 reduction ratio 

Figure 4.⎯Impact loads at various inclinations normal-ized

to vertical load for a single-particle drop in ore pass

simulation using WM2D 

PFC2D 

PFC2D is a distinct-element code designed to 

model complicated problems in solid mechanics and 

granular flow and is one product from a suite of geo- 
mechanics software tools from Itasca Corp. The 

calculation method in this code is a time-stepping, 

explicit scheme that is also called the “molecular 

dynamics” method (Luding et al., 1995). Contact laws 

using spring stiffness and damping are employed. The 

difference between WM2D’s event-driven method and 

PFC2D’s molecular dynamics method is the amount of 

contact time during particle collisions. In the eventdriven method, the time during contact is ideally zero 

(Luding et al., 1995), although WM2D utilizes the 

integration time-step that is set arbitrarily by the user 

to aid in calculating forces. In molecular dynamics 

simulations, contact time is dependent on initial velocities, spring stiffness, and damping. Impact calculations occur during a time period of elastic compression 

and release. 

 The standard particle shape in PFC2D is a circular 

disk or a sphere. Complex particle shapes can be built 

using a clumping technique. The perimeter of individual particles are defined by identifying polygon line 

segments around a group of tightly packed disks or 

spheres. 

Rock Properties and Simulation Inputs

 Both rock and soil-like properties have implications for flow when simulating rock flow. A sample 

from a U.S. mine was tested to evaluate these properties and to provide input into the simulations. 

 Blasted mine rock, whether it is ore or waste, 

contains a wide distribution of particle sizes. The 

largest sizes may become a handling challenge at an 

ore pass grizzly because, if allowed into the ore pass, 

boulders may cause a blocky hang-up somewhere 

along the flow route. The weight of a boulder is important to consider also, because it may affect impact 

loads. Particle size distribution and specific gravity of 

rock were considered in the ore pass simulations. 

 The fine fraction of the particle-size distribution 

curve has cohesive strength when water is added. 

Depending on the water content of the fines and the 

amount of compaction in the ore pass during filling, 

the fines could cause a hang-up. The fines also act as 

a binder around coarse particles, locking the bulk 

material together into one large mass. Knowing the 

amount of fines, the water content in the bulk material, 

and the strength of the fines will provide enough 

information to predict whether a hang-up will occur in 

an ore pass with a given design. The rock properties 

of interest are size, shape, weight, and elasticity 

Table 2.⎯Rock properties of interest for simulations 

Rock properties: 

 Modulus of elasticity 5.5e4 MPa (8.0 × 106

 psi) 

 Specific gravity 3.0 

 Particle size distribution (see figure 5) 

 Particle shape (see figure 6) 

Soil-like properties: 

 Internal friction angle (fines 

only), deg 

35 to 391

 Angle of repose at the mine, 

deg 

35.5 to 41 

 Angle of repose, dry (fines 

only), deg 

36 to 41 

 Sliding friction, static (fines 

only), deg 

25.4 dry, 40.0 wet 

 Sliding friction, constant 

velocity (fines only), deg 

22.6 dry, 34.5 wet 

 Percent fines 16.0 

 Uncompressive strength 

(fines only)1 4,700 to 13,000 Pa (0.68 

to 1.9 psi) 

 Water content (fines only), 

pct 

14.0 

1

Iverson (2002) 

(table 2). Figure 5 shows the size distribution of the 

rock from the sample. An ore pass simulation should 

match the actual size distribution at the mine as closely 

as possible. 

 Particle shape was determined for the PFC2D 

simulations using a three-view shadow. Front, side, 

and top views were shadowed for each particle 

sampled, and lines were drawn to that shadowed 

shape. Three outline views of a typical ore particle are 

drawn in figure 6 showing normal vectors from each 

side to the centroid from which angle and distance 

were modeled. A suite of 31 particles from three size 

fractions was sampled for shape. The number of sides 

was determined from 93 views of the 31 particles. 

Normal angles were determined from 33 views of the 

11 sized particles. 

 Data from these shape measurements are shown in 

tables 3 and 4 and were input into the ore pass 

simulations (figure 7). 

 Due to the limits of computer processing, the 

shape of the smallest rocks could not be simulated. A 

compromise was to pick a cutoff size for a shape 

simulation. The sizes below the cutoff value are represented by uniform sized spheres or disks. Particles at 

the cutoff size are considered the fine fraction. 
0

10

20

30

40

50

60

70

80

90

100

100 10 1 0.1

Particle size (inches)

Cummulative percent passing

Sample as

collected

Adjusted for

unsampled

boulders

PFC2D

Simulation

 Figure 5.⎯Mine-run ore size distribution compared to simulated distribution 

Figure 6.⎯Outline of typical ore particle showing top, 

front, and side views with normal vectors to each side for 

angle and distance measurements from the particle 

centroid

Soil-like properties are critical to understanding 

cohesive strength and hang-ups. The percentage of 

fines is a good indicator of potential problems. Beus 

et al. (2001) stated that 20% fines in the rock material

will form a continuous matrix, and the greater the fine 

fraction, the greater is the potential for cohesive arch

formation. Fines are considered to be particles less

than 0.074 mm (0.0029 in) in diameter or U.S. Standard 200 mesh (Beus et al., 2001). Water content and 

the amount of compaction of the wetted fines will 

determine cohesive strength. It is the authors’ contention that a combination of cohesive fines and interlocking of boulders can exacerbate a hang-up problem.

Figure 7.⎯Simulated falling ore particles with clumps 

based on shape and size distribution analysis

Table 3.⎯Variation in the number of sides for each size of 

rock measured

Large rock Medium

rock 

Small 

rock 

All sizes

No. of rocks 

measured 

11 10 10 31

Average no. of 

sides 

6.1 8.5 8.9 7.8

Standard 

deviation 

1.27 2.9 2.6 2.6

Average radius 0.0419 m 

(1.65 in) 

NM NM

Standard 

deviation 

0.56 NM NM

NM. Not measured 
Table 4.⎯Variations in angle between sides for large 

and medium rocks 

Sides, no. Views 

measured, no. 

Average 

angle 

between 

normal 

vectors, 

degrees 

Standard 

deviation 

3 1 120 9.2 

4 1 90 9.1 

5 11 72 22.3 

6 9 60 25.4 

7 6 51.4 21.0 

8 4 45 21.1 

9 1 40 24.1 

 For simulation purposes, friction of the rock and 

the soil-like material is important. Friction properties 

(internal angle of friction, angle of repose of piles, 

angle of repose of fines, and sliding friction angle of 

dry and wetted fines) were obtained from laboratory 

experiments. Internal friction angle was used for 

friction coefficient of the particles in the simulation. 

The repose and sliding angles can be compared with 

sliding material simulations in PFC2D. Wall friction 

coefficients and particle friction coefficients can be 

adjusted. 

 In simulating the fine fraction in PFC2D, bonding 

between particles was used to represent the cohesive 

strength of the material. Two-dimensional unconfined 

compressive strength tests were simulated based on 

laboratory tests of the fine fraction (Iverson, 2002). 

 PFC2D simulation inputs used are shown in table 

5. Particle stiffness was determined from the modulus 

of elasticity value. Larson et al. (1998) provides a 

conversion to particle stiffness using the following 

equation: 

 Kn = ArE 

where Kn = particle stiffness, N/m, 

 A = dimensionless constant (determined to be 

0.19052), 

 r = particle radius, m, 

and E = modulus of elasticity, Pa. 

Table 5.⎯PFC2D simulation inputs 

Particle density 3000 kg/ m3

Cutoff particle radius 0.0127 m 

Particle type (disk or ball) ball 

Cohesion bond strength 5000 Pa (0.7 psi) 

Particle stiffness (normal 

and shear) 

1.3e8 N/m (8.9e6 lb/ft) 

Bond stiffness (normal and 

shear) 

1e8 N/m (6.9e6 lb/ft) 

Steel chute stiffness 4.8e8 N/m (3.3e7 lb/ft) 

Particle friction coefficient 0.73 

Wall friction coefficient 0.73 wall rock, 0.17 steel 

chute 

Grizzly spacing 0.381 m (1.25 ft) 

Ore pass width 3.0 m (9.8 ft) 

Ore pass angle Variable 

Chute angle 45 degrees 

Chute gate opening height 0.91 m (3 ft) 

Ore pass height 91.4 m (300 ft) 

 Larson et al. (1998) also indicate that the angle of 

repose is reasonable for use as a friction coefficient in 

PFC2D. 

Simulated Single-Particle Drop Test

 A single-particle drop test was run in PFC2D 

using the same parameters as in the WM2D test. Since 

there is no input in PFC2D for e, the elasticity of the 

impact had to be obtained by using a special contact 

model. The stiffness of the impact was decreased 

during the second half of the collision. By adjusting 

rebound stiffness, a comparable e was accomplished. 

Dynamic loads produced in PFC2D were much higher 

than in WM2D. The impact period or integration 

time-step used in WM2D was 0.196 sec, much longer 

than in PFC2D. Particle and wall stiffness affect 

dynamic load significantly in PFC2D. When drop 

height was zero, PFC2D produced a dynamic peak 

load twice the final static load. Data from the drop test 

are shown in table 6 and figure 8. Dynamic loads were 

large compared to the later ore pass simulations 

because particle size in the single-particle drop test 

was large compared to individual particle sizes in the 

ore pass simulations. 
Table 6.⎯Single-particle drop test data from PFC2D 

Drop height Rebound e Dynamic load

m ft m ft kN lb-force

0 0 0 0 0 60 1.0e4

10 30 0.8 2.6 0.283 45,710 1.02e7

15 49 1.05 3.4 0.265 57,800 1.30e7

20 66 1.1 3.6 0.235 66,910 1.504e7

25 82 1.5 4.9 0.245 75,120 1.689e7

30 98 1.85 6.1 0.248 82,430 1.853e7

35 115 2 6.6 0.239 87,910 1.976e7

40 131 2.2 7.2 0.235 94,440 2.123e7

45 148 2.4 7.9 0.231 97,510 2.192e7

50 164 2.6 8.5 0.228 104,200 2.343e7

0

20000

40000

60000

80000

100000

120000

0 20 40 6

Drop height (m)

Dynamic loading (kn)

0

Figure 8.⎯Peak dynamic loads from PFC2D single-particle 

drop test simulations 

Inclined Ore Pass Simulations

To simulate the effects of ore pass inclination, 

rock particles were dumped into the ore pass at various 

angles of inclination, and dynamic loads were measured at the bottom end (table 7). Figure 9 illustrates 

the setup for an inclination of 65° with a grizzly at the 

top end and a chute at the bottom.

The material was generated at the top of the 

simulated ore pass just above the grizzly (figure 10). 

Figure 10 is a close-up view of an ore pass setup similar to that shown in figure 9, but at 80° inclination. 

The small rectangles represent the bars of a grizzly. 

Material passing through the grizzly was "metered," 

much like what occurs at the top end of an ore pass in

a real mine environment. The PFC2D dynamic loads 

at the ore pass bottom are shown graphically in

Table 7.⎯PFC2D simulation results showing peak 

dynamic load and inclination 

Ore pass 

inclination, 

degrees 

Peak dynamic load 

N lb-force

90 125,000 2.81e4

80 92,140 2.07e4

70 86,300 1.88e4

60 67,500 1.52e4

50 58,900 1.32e4

figure 11. Observations during peak impacts indicate 

single-particle impacts represent peak dynamic loads.

Dogleg Simulation

The inclined ore pass with a short dogleg transition into the chute was used to compare forces at the

dogleg with forces at the chute gate (figure 9). Figure 

12 provides a close-up view of the PFC2D simulation 

and shows rock striking the chute slide, followed by 

impacts to the chute gate. Figure 13 is a graph of 

dynamic force over time acting normal to the chute 

slide and the chute gate. A comparison of both graphs 

in figure 13 shows that the chute slide was subjected to

greater impulsive force from the stream of rock. Peak 

forces were 58,630 and 13,490 N (13,180 and 3,033 

lb-force) on the chute slide and gate, respectively.
Figure 9.⎯PFC2D ore pass simulation setup for a 65°

inclination 

Figure 10.⎯PFC2D grizzly dump simulation using angular 

clumped particles and cohesive bonding for fine material 

0

50000

100000

150000

50 60 70 80 90

Inclination, degrees

Dynamic load, kn 

Figure 11.⎯Ore pass inclinations and peak impact load from

PFC2D simulation 

Final static loads on the chute slide and gate were 600 

and 425 N (135 and 95.5 lb-force), respectively. The 

duration of impacts for the chute slide and gate were

1.6 and 1.2 sec, respectively. The total mass of the 

dump was 84.3 kg (5.78 slugs), providing a static 

weight of 827 N (186 lb-force). 

Hang-Up Release Simulation

A hang-up release simulation was run for a 91.4-m

(300-ft) vertical ore pass without a grizzly. In this 

simulation, particles remained tightly packed until they 

struck the chute slide below. This impact simulated

the sudden release of a hang-up in which a large mass 

of rock fell as a unit onto the bottom end chute. Peak 

dynamic force normal to the chute slide wall in this 

test was 6.7 times the peak force measured in the 

vertical ore pass simulation with a grizzly (figure 14).

Peak impact forces for the slide and gate were 390,800

and 191,800 N (87,860 and 43120 lb-force), respectively. Final static loads on the slide and gate were 

800 and 550 N (180 and 124 lb-force), respectively.

Duration of impacts for the slide and gate was short, 

about 0.2 sec combined. The total mass of the dump

was 75.3 kg (5.16 slugs), providing a static weight of

739 N (166 lb-force). Packing into the chute area was

greater in this simulation than in the simulation in 

which a grizzly was used over the ore pass, which

resulted in greater static forces. 
Figure 12.⎯PFC2D simulation of angular rock particles

striking chute slide and gate 

DISCUSSION AND CONCLUSIONS 

PFC2D can be made user friendly by programming specific dimensions or features into the simulation. Ore pass angle, chute slide angle, chute opening

angle, chute length, and grizzly spacing are some of

the variables worth manipulating in the design of an

ore pass. With some additional effort, grain-size distribution and particle shape can also be simulated. 

PFC2D was used to compare dynamic forces at the

bottom end of a chute with various ore pass angles. 

Forces on chute slide and gate components were also

compared. As a two-dimensional simulation, forces 

on the bottom at the dogleg or at the chute were much

less than what would be expected in a threedimensional simulation or in a real-case ore pass 

scenario. Individual unclumped spherical particles

simulated in two dimensions are comparable to a 

three-dimension situation. 

The cohesive nature of fine particles can be 

modeled using PFC2D bonds. There is a limit to the 

number of particles that can be simulated because of

limitations in the capabilities of personal computers.

This can be remedied by using a cutoff particle size 

and model that fraction as cohesive fines. Single rock

impacts, rock streams, and released hang-ups were all

Figure 13.⎯Dynamic force on chute slide and gate from one 

dump event analyzed with PFC2D 

simulated using PFC2D. The force of individual

impacts measured in the simulations were high, but

represent the elasticity of the materials simulated. 

These forces may be slightly overestimated, considering that rock will fracture during impact and absorb 

some of the collision energy over a longer impact 

period. Also these simulated collisions do not account 

for flexure of an impact surface, such as a steel plate

that is part of a chute assembly. 

WM2D was also useful in measuring dynamic

forces and testing flow designs. Dynamic load values 

are suspect because of the arbitrary use of the integration time-step and its effect on normal force. With 

such a large time-step used, force values may be

severely underestimated. Design considerations can

be tested using various inclinations, doglegs, and chute 

configurations in WM2D. 
Figure 14.⎯Impact forces on chute slide and gate following

a hang-up release analyzed using PFC2D 

Testing ore pass designs using either program

takes computer simulation time and computer resources. Which type of simulation is best was not 

determined. The event-driven simulation using 

WM2D may have advantages in processing time due 

to the nature of its calculation cycle. PFC2D requires 

time-stepping during compression and relaxation of 

each particle collision whereas WM2D does not. 

Higher particle velocity requires a smaller time-step

during cycling in both PFC2D and in WM2D. PFC2D

has the capability of modeling cohesion using bonds

whereas WM2D does not. 

Although the impact forces are somewhatsuspect,

the use of inclined ore passes and doglegs to reduce

impact force on the chute was demonstrated using 

PFC2D and WM2D. 

REFERENCES 

Beus, M.J., W.G. Pariseau, B.M. Stewart, and S.R.

Iverson. 2001. Design of Ore Passes. Ch. 71 in 

Underground Mining Methods: Engineering Fundamentals and International Case Studies, Hustrulid and 

Bullock, eds. Society for Mining, Metallurgy, and 

Exploration, Inc., pp. 627-634. 

Itasca Consulting Group, Inc. (Minneapolis, MN).

1995 PFC2D (Particle Flow Code in 2 Dimensions), 

Version 2.0. 

Iverson, S.R. 2002. Investigation of Bulk Solids 

Engineering Properties and Application of PFC2D to

Ore Pass Flow Problems. In Numerical Modeling in 

Micromechanics via Particle Methods. Proceedings of 

the 1st International PFC Symposium, ed. by H.

Konietzky (Gelsenkirchen Germany, Nov. 6-8, 2002).

Balkema, Rotterdam, Netherlands, pp. 252-258. 

Larson, M.K., S.R. Iverson, B.M. Stewart, and K. 

Walker. 1998. Preliminary Assessment of Particle

Flow Code as a Tool To Assess Ore Pass Safety. 

Presentation at Rock Mechanics in Mining, Petroleum,

and Civil Works: 3rd N. American Rock Mechanics

Symp. (Cancun, Quintana Roo, Mexico, June 3-5,

1998), paper 92. Extended abstract in International 

Journal of Rock Mechanics & Mining Science, vol. 35, 

nos. 4-5, p. 533, 1998. (Available on CD-ROM from 

Elsevier, New York, NY) 

Luding, S., E. Clement, A. Blumen, J. Rajchenbach, and J. Duran. 1995. Interaction Laws and the 

Detachment Effect in Granular Media. Symposium 

Proceedings, Materials Research Society, Pittsburgh, 

PA, vol. 367, p. 495. 

MSC Software Corp. (Santa Ana, CA). 2002. 

Working Model 2D. 

Pariseau, W. G. 1996. Role of Material Properties 

in Ore Pass Design. Unpublished contract report to 

NIOSH, 23 pp. 
COMPARISON OF ORE PASS COMPUTER SIMULATIONS FOR DESIGNS AGAINST 

DYNAMIC LOAD 

S. Iverson 

Spokane Research Laboratory, National Institute for Occupational Safety and Health, Spokane, WA 

siverson@cdc.gov 

S.J. Jung and K. Biswas 

University of Idaho, Moscow, ID