©THEBRIGHTSTARS 2024
CMP 305 Exam Questions With Revised
Answers
Site Investigation: Necessities for planning construction techniques - answer✔✔Site Access,
Type of construction equipment, ground water, surface water development
Documents for Evaluating the site - answer✔✔Soil Maps, topographic maps, aerial photographs,
USGS topographic quadrangle maps
Info obtained from soil profile - answer✔✔uniform soil conditions, number of borings and bore
spacing, type - size - weight of structure
Bore spacing for road work, one story building, multi story - answer✔✔Road - 500-1000'
one story - 100-200'
multi story - 50-100'
How far down does boring depth have to be? - answer✔✔until suitable soil bearing capacity is
found and depth of ground water(if needed)
Direct Exploration - answer✔✔Uses Test pit method, pit or trench, visual inspection, limited
depth 15-20', equipment: backhoe or excavator.
Advantages of Direct exploration - answer✔✔view soil profile(type and color)
obtain undisturbed sample
Disadvantages of Direct exploration - answer✔✔limited depth, ground water may limit depth,
safety(soil caving in)
Devices for in-place soil testing - answer✔✔Pocket penetrometer(TSF), torvane, thumb
penetration
Semi-direct exploration - answer✔✔Auger Drilling
Auger Types - answer✔✔Solid Auger: dry regions, auger removed for sampling(hole will
collapse), Hollow Auger: sampling thru the auger, faster taking samples, (split barrel, shelby
tube).
, ©THEBRIGHTSTARS 2024
Rotary Drill - answer✔✔auger with clay slurry, slurry moves soil up, slurry stabilizes the sides
of the drill hole
Cone Penetrometer - answer✔✔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 - answer✔✔Road work, fast, quick results, less expensive. Seismic
refraction and electrical resistance.
Seismic refraction - answer✔✔velocity of seismic wave transmitted through soil. greater density
- faster waves.
Drilled Samples - answer✔✔Disturbed samples
why do we sample - answer✔✔use for grain size analysis, liquid limits, plastic limits and plastic
index
Testing with Undisturbed samples - answer✔✔Split barrel, shelby tube or test pit
Split barrel or standard penetration test(SPT) - answer✔✔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 - answer✔✔OD=2", Length=30", Sample
OD 1 5/8", hammer wt.= 140#, Drop height=30"
how does Standard Penetration Test work - answer✔✔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 - answer✔✔Dia. 2-5", Length 4"
How does Shelby Tube work - answer✔✔Tube is pushed in, used with the hollow core auger,
Sampling interval 5'
Why is it important to know location of ground water table - answer✔✔effects the soil load
bearing capacity, type and size of foundation required, dewatering system, plan for drainage,
Permeability of Soil - answer✔✔Property of soil to transmit water and air
Compaction - answer✔✔Process of increasing soil density by mechanically forcing particles
together. Removes air from void space. accomplished in matter of hours.
