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REV90902
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Entry Properties
Last modified
8/25/2016 3:12:32 AM
Creation date
11/21/2007 11:07:49 PM
Metadata
Fields
Template:
DRMS Permit Index
Permit No
M1977210
IBM Index Class Name
Revision
Doc Date
7/6/1989
Doc Name
SAFETY IN THE USE AND MAINTENANCE OF LARGE MOBILE SURFACE MINING EQUIPMENT
Type & Sequence
AM3
Media Type
D
Archive
No
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90 <br />designed stopping potential of the berm. <br />Rolling over onto the roadway is deemed <br />better than vaulting over an elevated <br />roadway. <br />A rigidly constructed berm represents <br />an approximation of the minimum berm <br />height required to restrain an errant <br />haulage vehicle. Impacting a similar <br />size berm constructed from a deformable <br />material will result in a vehicle either <br />penetrating the berm or vaulting over it. <br />While the deformable material will offer <br />increased rolling resistance, its reduced <br />strength may allow a shear failure of the <br />berm tip resulting from vehicle loading. <br />Therefore, the smaller the berm size, the <br />more rigid it must be. <br />Curves were prepared for the 35-, 85-, <br />and 170-ton haulage trucks from the scale <br />model simulations, computer simulations, <br />and full-scale field tests. A convenient <br />way of presenting the predicted berm <br />height is as a multiple of the axle <br />height of the largest haulage vehicle <br />using the roadway. When this ratio is <br />plotted against the rira sinkage value <br />that corresponds to berm strength, typi- <br />cal curves represented in figure 2 re- <br />sult. When the berm is weak, a large <br />berm height is required to stop an errant <br />vehicle through the mechanism of berm <br />climb and berm penetration. At interme- <br />diate berm strength, the kinetic energy <br />of the vehicle is absorbed by berm climb, <br />berm penetration, and, eventually, roll- <br />over; but now a much smaller berm is re- <br />quired. The smallest berm that can re- <br />strain a runaway vehicle has its strength <br />increased by compaction. The smallest <br />berm is the most economical to build be- <br />cause it does not require the excessive <br />road width required by weak berms. An <br />ideal high-strength berm has no tare <br />sinkage, and the energy of the vehicle is <br />absorbed by berm climb, as exhibited by <br />redirection at shallow approach angles or <br />by rollover onto the roadway at speeds in <br />excess of berm stopping capability. <br />Figure 2 shows that the smallest allow- <br />able deformable berm fora 35-ton truck <br />is one that is three times the axle <br />• <br />height at a strength of 3 in of tare <br />sinkage measured at axle height on the <br />berm. For an 85-ton truck, a three- <br />times-axle-height berm is required at a <br />strength of 2.3 in of rira sinkage mea- <br />sured at axle height on the berm. For a <br />170-ton truck, a four-times-axle-height <br />deformable berm is required at a strength <br />of 2.3 in of rira sinkage measured at <br />axle height on the berm. These figures <br />are conservative by at least one axle <br />height over rigid berm requirements. <br />As a result of these simulations, berm <br />height recommendations, for significantly <br />compacted berms, can be categorized by <br />the vehicle size. For vehicles whose <br />load-carrying capacity is 85 tons or <br />less, the compacted berm height recommen- <br />dation is specified to be three times <br />axle height; for haulage vehicles larger <br />than 85 tons, the compacted berm height <br />recommendation is four times the axle <br />height. <br />Berms can be constructed and compacted <br />in layers to meet these recommendations. <br />The face of the berm should then be cut <br />at a steep angle (40°) to minimize the <br />KE KE ~r011over, KE -re tlirettla <br />berm berm climb, rollover, <br />climb, penetr a ton berm climb <br />penetration <br />r <br />2 <br />C7 <br />w <br />x <br />f <br />m <br />S <br />~_ <br />W <br />x <br />io <br />w <br />J <br />Q 8 <br />KEY <br />Ma.imum approach con dilip na <br />3p mph, 3p• <br />Berm elope, t0r <br />35-ton haulage renici e. <br />rira witin-ta in, <br />a aia nei9 nr-30 i <br />--- es-ton na uie qe ren~ci a. <br />rira width-2d in, <br />a •19 neight-50 i <br />-'-~ 170-ton haulage rahicl e. <br />tna r~°tn-3e in. <br />a ale neight-5) in <br />20 10 5 4 3 - <br />BERM STRENGTH AS DETERMINED <br />BY TIRE SINKAGE, in <br />FIGURE 2. - Berm size requirement as a func- <br />tion of berm strength for 35-, 85-, and 170- <br />ton haulage vehicles. (K E kinetic energy) <br />• <br />
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