CMP 305 Exam Questions and Answers
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Site Investigation: Necessities for planning construction techniques -
✔✔Site Access, Type of construction equipment, ground water, surface
water development
Documents for Evaluating the site - ✔✔Soil Maps, topographic maps, aerial
photographs, USGS topographic quadrangle maps
Info obtained from soil profile - ✔✔uniform soil conditions, number of
borings and bore spacing, type - size - weight of structure
Bore spacing for road work, one story building, multi story - ✔✔Road - 500-
1000'
one story - 100-200'
multi story - 50-100'
How far down does boring depth have to be? - ✔✔until suitable soil bearing
capacity is found and depth of ground water(if needed)
Direct Exploration - ✔✔Uses Test pit method, pit or trench, visual
inspection, limited depth 15-20', equipment: backhoe or excavator.
,Advantages of Direct exploration - ✔✔view soil profile(type and color)
obtain undisturbed sample
Disadvantages of Direct exploration - ✔✔limited depth, ground water may
limit depth, safety(soil caving in)
Devices for in-place soil testing - ✔✔Pocket penetrometer(TSF), torvane,
thumb penetration
Semi-direct exploration - ✔✔Auger Drilling
Auger Types - ✔✔Solid Auger: dry regions, auger removed for
sampling(hole will collapse), Hollow Auger: sampling thru the auger, faster
taking samples, (split barrel, shelby tube).
Rotary Drill - ✔✔auger with clay slurry, slurry moves soil up, slurry
stabilizes the sides of the drill hole
Cone Penetrometer - ✔✔Holland, US & Canada, pushed into the ground,
records readings in different sections. Adv: provides a continuous record of
test results used for engineering properties for the entire profile
Geophysical Testing - ✔✔Road work, fast, quick results, less expensive.
Seismic refraction and electrical resistance.
Seismic refraction - ✔✔velocity of seismic wave transmitted through soil.
greater density - faster waves.
, Drilled Samples - ✔✔Disturbed samples
why do we sample - ✔✔use for grain size analysis, liquid limits, plastic
limits and plastic index
Testing with Undisturbed samples - ✔✔Split barrel, shelby tube or test pit
Split barrel or standard penetration test(SPT) - ✔✔tube used to collect soil
sample at the bottom of the test hole. pass through the hollow tube auger,
measurement - resistance to penetration
Split barrel Specs.
OD, Length, Sample OD, Hammer wt., Drop height - ✔✔OD=2",
Length=30", Sample OD 1 5/8", hammer wt.= 140#, Drop height=30"
how does Standard Penetration Test work - ✔✔sampler is driven for 3
consecutive 6" increments. Count number of blows per 6" increments, Blow
count summation(take last two sets of numbers)
Shelby Tube dimensions - ✔✔Dia. 2-5", Length 4"
How does Shelby Tube work - ✔✔Tube is pushed in, used with the hollow
core auger, Sampling interval 5'
Why is it important to know location of ground water table - ✔✔effects the
soil load bearing capacity, type and size of foundation required, dewatering
system, plan for drainage,
