test 1 Flashcards
view from above
plan/top view
view from side
side view
view from under
bottom view
angled view
isometric view
what is the bottom point of a bench called?
the toe
what is the angle between the pit floor and line drawn to the surface?
overall slope angle
what is the point of the bench closest to the middle of the bench called?
crest
what is the angle between horizontal and a line between two toes called?
interramp angle
purpose of a bench?
safety: improve stability and stop/catch material
operational: easier to mine and grade control
face angle and overall slope angle factors
geomechanics and economics. steeper is more economical but less safe.
normal face angle
55 to 80 degree
which angle changes with mine life?
overall slope angle and interramp angle
what is the final bench width?
approx 1/3 of the bench height
how can benches in the final pit be different?
may have double benches followed by single bench catches of double width
where are berms necessary?
where drop offs exist of sufficient grade or depth to cause a vehicle to overturn
how tall must berms be?
mid axle height of largest self propelled vehicle which usually travels the roadway
when can you not have berms?
infrequently traveled roads
when can you not have berms?
infrequently traveled roads
what must you have to not have berms?
locked gates and warning signs
typically impact zone width to catch material on a bench?
3 to 5 m
what is the strip ratio?
amount of waste rock which must be removed per unit ore. or inverse. may be any combination of weight or volume
what is highest typical strip ratio seen?
1:10 weight to weight
typical density of unbroken rock
2.7 tonne per cubic meter
specific gravity?
ratio of density of material to density of water
how much does rock expand when broken?
30% is a good estimate
unbroken volume also called?
bank volume
3 types of surface mining
open pit, strip mining, specialty
features of an open pit?
bowl shaped, overburden piled outside the pit in a dump, slopes are stepped/benched
what determines bench height?
the equipment used
which cfr title is msha under?
30
features of a strip mine?
mined in strips, overburden dumped into previously mined strip, for bedded deposits
other types surface mining
dredging, highwall mining, suction dredge
dumps are classified according to?
material type, location, construction
2 types of low or no economic value dumps
overburden and tailings storage facility
dumps that contain value
ore stockpiles, heap leach
dump forms
valley fill, cross valley fill, side hill fill, ridge crest fill, heaped fill
ascending or descending dump build more stable?
ascending, small lifts even more so
key to blocks on block model
economic value
block size determiners
mining method, data density
example block size?
one day production
example block height?
bench height
value of a block=
revenue-costs
what is floating cone method?
cone shape of blocks is progressively analyzed through block model. value is net profit
3 optimization techniques
floating cone, lerchs-grossmann, genetic algorithms
keys to road design
safety, structural, economics
sae recommended braking distance at 20 mph dry, level ground
200-400k lbs=125ft
400k+ lbs=175ft
stopping distance key factors
road condition, weather, grade/slope, equipment size, brake tech, reaction time
grade=
vertical/horizontal
rolling resistance
friction of tires, restricts movement, minimizes braking distance and achievable max speed
effective grade
downhill: grade-RR
uphill: grade+RR
typical sustained grades
no more than 8-10%
mines avoid more than x grades
15-20%
how to increase sight distance in the vertical
flatten vertical curves
how to increase sight distance in horiz curves?
remove obstructions or widen curves
road width on straights
lane+berm+drainage
lane width
single: 2 times largest truck
double: 3-4 times largest truck
if berm is made of large boulders?
must be same height as tire
main berm purpose
-visual indication of road
-provide sensation of contact
-provide opportunity to regain control
-keep vehicle back from edge of slope
typical drain
10 by 2 feet
when grass line ditch
3-5% grade
when rock lined ditch
5+% grade
road cross slope
1/4 to 1/2” drop per foot. 1/4” when slippery
change from cross-slope to bank
runout
___ the speed, ___ the change in cross-slope
higher, slower
types of escape ramps
high rolling resistance material or uphill or berm
center berm
must be made of fine material, not too far apart
4 road layers
wearing surface, base, subbase, subgrade
which road layer not always needed or used
subbase
wearing surface material
fine crushed rock
base surface material
coarse crushed rock
subbase surface material
clean, granular material
subgrade material
compacted rock or soil
typical load distribution for truck
1/3 front 2/3 rear
increasing TIP
improves mpg and puts more pressure on road
increase tire load by x for dually
20%
CBR
california bearing ratio
good x reduces rolling resistance
adhesion
in pit pond called
sump
ponds should
settle sediments, offer storm surge capacity
infiltration basins
send water into groundwater table, discharge less
surface runoff design
drainage area, max snow/rain, runoff quantity
rain to plan for
24/48 records, 100 yr records
runoff quantity methods
rational method and soil conservation service method
rational method
gives proportion that will runoff
law for settling sediments
stokes law
settlement pond
2:1 length to width
how many sediments should pond hold
3 yrs worth
ditch velocity
2-3ft/s for sand
5-7ft/s for veg
