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210 Cards in this Set
- Front
- Back
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What affects the engineering properties of granular soils |
grain size and shape grain size distribution and compactness |
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What are some engineering properties of granular soils |
-ability to support large load bearing capacities -little settlement -good foundation material for roads and structures -backfill material for retaining walls, easily compacted and drained -high shear strengths -good embankment material (except in earthen dikes and dams) |
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What are some engineering properties of cohesive soils |
-good for earthen dikes and dams due to low permeability -used as a liner for landfills -damp proofing |
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What are some undesirable properties of cohesive soils |
-low shear strength compared to granular, especially when wet -plastic and compressible, expands when wet, shrinks when dry -creeps over time under constant load (landslides) -develops large lateral forces |
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What are engineering properties of silt soils |
silt is fine grained like clay, but non cohesive like sand |
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what are undesirable properties of silt soils |
high capillary action and susceptible to frost action, yet low permeability and low density |
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What are the engineering properties of organic soils |
-none, it is usually spongy, crumbles, and is compressive -has low shear strength |
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What is the first step in the unified system for field testing soils |
remove particles larger than 3" diameter first |
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Which step follows removing 3" diameter pieces in the unified system for the field testing of soils |
separate pieces larger than the 200 sieve. If more than 50% of the soil by weight is larger than the #200 sieve, it is coarse grained soil |
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Which step follows separating all particles larger than the 200 sieve in the unified system for field testing of soils |
particles are divided into pieces larger and smaller than 1/4" in diameter, if more than 50% by weight is larger then it is classified as gravel, otherwise it is sand |
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What step follows dividing pieces into larger and smaller than 1/4" in diameter in the unified system for field testing of soils |
if less than 10% of total sample is smaller than the 200 sieve, the second letter is assigned based on grain distribution - W for well graded, P for poorly if more than 10% is smaller than the #200 sieve, the letter is based on the plasticity of the fines - L for low plasticity, H for high plasticity |
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What step follows the 10% total weight sample in the 200 sieve in the unified system for field testing of soils |
If sample is fine grained (more than 50% by weight is smaller than the 200 sieve) classification is based on dry strength and shaking tests of the material smaller than 1/64 in diameter |
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What are the steps used in dry strength testing |
-mold into ball, add water to make putty, let it dry -break ball with thumb, if you cannot then it is highly plastic -if it breaks but difficult to powder it is medium plasticity -if it powders easily, it is low plasticity |
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What are tension cracks |
usually occur at 0.5 to 0.75 times the depth of the trench, measured from the top of the vertical face of the trench |
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What is sliding? |
may occur as a result of tension cracks, it is a function of soil type and measure |
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what is toppling? |
the trench's vertical face separated down the tension crack and rolls into the trench |
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What is subsidence or bulging? |
An unsupported trench wall can create an unbalanced stress in the soil, causing the surface to subside and bulging of the vertical face of the trench wall |
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What is heaving or squeezing? |
bottom shifting up is caused by the downward pressure created by the weight of the adjoining soil. This causes a bulge at the bottom of the cut. Heaving can occur when shielding is properly installed |
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what is boiling? |
upward flow of water into the bottom of the cut caused by a high water table, this condition can occur when shielding is properly installed |
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Sieve analysis |
Shaking the soil sample through a set of _____'s that have a progressively smaller opening. Used to find particle size distribution of the soil. Min. 0.075 mm |
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Hydrometer Analysis |
Based on the principle of sedimentation of soil grains in water when soil specimen is dispersed in water, the particles settle at different velocities, depending on their shape, size, weight, and viscosity of the water. It is assumed that all soil particles are spheres, and the velocity of soil particles can be Stokes' law |
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Atterberg limits |
-plastic limit is defined as MC in percent at which soil crumbles when rolled into threads of 118 in. in diameter -The plastic limit is the lower limit of plastic stage of soil. -test is simple and is performed by repeated rollings of an ellipsoidal size soil mass by hand on a ground glass plate |
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a Liquid Limits Test |
-consists of a brass cup and a hard rubber base -place soil in cup and cut a groove at the center -then drop the cup from .4 in. -the MC in percent, required to close a distance of 0.5 in along the bottom of the groove after 25 blows is defined as the liquid limit |
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The degree of compaction of a soil is measured by |
Its dry unit weight |
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Compactions in general is |
the densification of soil by removal of air |
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When water is added to the soil during compaction |
it acts as a softening agent on the soil particles, then the soil particles slip over each other and move into a densely packed position |
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Standard Proctor Test |
Test compaction by dropping a 5.5 lbs. hammer that drops 12 inches, delivers 25 blows to each of the three equal layers |
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Consolidation soil settlement |
result of time dependent consolidation due to an applied load |
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Sand Cone method |
Consists of a glass jar with a metal cone attached to the top, filled with dry ottowa sand, the weight of the jar, the cone, and the sand is determined. if the weight of moist soil excavated from the hole is determined, the dry weight of the soil can be obtained |
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Topographic Map |
a map that uses contour lines to show elevations in an area |
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USGS Topographic Quadrangle Maps |
Digital maps produced by the _____ that show where certain types of soils reside in an area |
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What are some of the steps in Surface Evaluation |
Visit the site, check the water level, discover underground utilities, and talk to local residents about the land and its features |
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What are some of the steps in subsurface evaluation |
-locate the vertical and horizontal boundaries of soils and rock underneath the site -locate ground water table -obtain samples of various depths -created hazard analysis |
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Soil Boring |
Spacing and depths are both obtained from the soil profile |
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What is a soil profile |
shows where the soil type in ground changes |
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what is the area of change known as in a soil profile |
a horizon |
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In soil bearing continue to bore into the earth until |
a suitable soil bearing capacity is found |
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Test Pit (Direct Exploration) |
A direct observation of subsurface material by digging a trench which is then observed. -has a limited depth of 15-20 ft. due to equipment used |
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Advantages of a Test Pit |
View the soil profile first hand and is an undisturbed sample |
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Disadvantages of a Test Pit |
limited depth, ground water can limit observable depth, and is not as safe as other methods |
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In-place Soil Tests: Pocket Penetrometer |
pocket device that is used to test compressive strength of a soil by pushing into the sample, can be used to determine if a trench needs shoring. Does not replace lab testing |
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What does a Pocket Penetrometer indicate |
the consistency, shear strengthen and approximate unconfined shear strength |
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In-Place Soil testing: Torvane |
hand held vane shear device for rapid determination of shear strength in cohesive soils in either laboratory or the field
Used in sides of test pits, trenches, or excavations |
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In-Place Soil Testing: Thumb Penetration Testing |
The pressing of your thumb into a flesh clump of soil |
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Type A thumb penetration |
thumb only makes a small indent into the soil with great effort |
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Type B thumb penetration |
thumb will sink into the soil up to end of your thumbnail |
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Type C thumb penetration |
Your whole thumb goes all the way into the soil clump |
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Auger Drilling (Semi-Direct Exploration) |
can be hand or truck mounted |
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Solid Auger (SDE) |
Used in dry regions with no ground water, auger is removed for a sample and hole is collapsed |
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Hollow Auger (SDE) |
Auger goes down and sample is contained in the stem, it is faster than a solid auger, the sample is disturbed |
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What are the two types of Hollow Augers |
Shelby Tube and Split Spoon |
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Split Spoon |
Driven into the ground in three groups of 6" blows to the soil |
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Shelby Tube |
a hollow auger that is continually pushed (not drilled) into the ground |
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Rotary Drill (SDE) |
auger with a clay slurry that moves soil up, which stabilizes sides of the drill hole |
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Wash Boring (SDE) |
Drilling that uses a jet of water, chasing is required |
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What are the advantages and disadvantages of wash boring |
ADV: small DIS: disturbed soil |
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When drilling into rock what type of drill should you use |
a diamond or carbide tipped |
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What is Rock quality Designation (RQD) |
a measure of rock integrity based on the condition of core samples |
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Cone Penetrometer (SDE) |
pushed into the ground which records readings for different sections |
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What are the advantages and disadvantages of a cone penetrometer |
ADV: continuous results and engineering properties DIS: No sample for lab testing |
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What is a drilled sample |
a disturbed sample that is used for grain size analysis. liquid and plastic limits, and plastic index |
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Split Barrel, Shelby tube, and the test pit are all forms of what kinds of samples |
undisturbed |
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Split Barrel or Standard Penetration Device (SPT) |
a tube used to collect samples at bottom of test hole where soil passes through a hollow tube auger |
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What does a Split Barrel or SPT find out |
soil classifications and identifications, and measures a soils resistance to penetration. It is driven into the ground |
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What is unique to a Shelby Tube |
-it is pushed continuously into the ground -it is a thin wall tube to obtain an undisturbed sample -it has a sampling interval of 5 |
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Ground Water Table |
the area of the ground in which the soil is completely saturated with water |
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Why is the ground water table so important to engineers |
it effects the soils load bearing capacity, this info is used to determine size of the foundation that is needed |
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When does the water table change |
with the change of seasons |
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after boring into the ground what should you do |
check for ground water |
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What is the adequate thickness for concrete sidewalks |
3-5" |
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whats is the adequate thickness for driveways |
4-8" |
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What is the adequate thickness of roads |
6-14" |
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What is the adequate thickness of airports |
8-24" |
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What are the three major types of portland cement |
reinforced, non reinforced and roller compacted |
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In reinforced portland cement what are the three types |
steel fibers (SFRC), Light mats/bars (JRPC), and Heavy Bars (CRPC) |
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What is long term pavement |
pavement planned to last 50-1000 years |
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What is heavy foundation used for in long term pavement |
to minimize sub grade damage |
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what is short term pavement |
pavement planned to last 10-20 years, light foundation which allows for sub grade damage |
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What is the number 1 failure of pavement |
poor drainage |
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What do all pavements rely on |
solid base with optimum MC |
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When an asphalt base loses its rigidity what happens |
pavement will settle, overflex, or crack |
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When inspecting concrete, what should you look for |
look for moisture at cracks, joints, and low points |
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What are the weights of light, heavy and normal concrete |
L: 30-90 lbs per cu. ft H: 180-400 lbs. per cu. ft N: 140-190 lbs. per. cu. ft. |
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What is a concrete mix |
portland cement, aggregate, water, and additives |
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What does trench stand up time depend on |
-depth of trench -slope of trench wall -fissures/tension cracks -soil type -soil MC -location of water table -weather -surface surcharge -vibrations |
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If trench is deeper than 5 feet what do you need |
some type of protection (shoring)
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If it is deeper than 4 feet |
a means of egress is needed every 25' |
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Temporary piles must be how far from the edge |
at least 2 feet |
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Directional Boring, what are the benefits |
only disturbs point of entry/exit |
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What are the three classification systems of trenches |
horizontal boring, pipe jacking, and tunneling |
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What is horizontal boring |
forcing a hole through soil and pull the pipe in |
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What is pipe jacking |
working from a vertical shaft with massive push block |
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What is tunneling boring machine |
self contained machine with cutting face to cut and remove soil |
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What are the two types of pipe repair without excavation |
pipe relining and pipe bursting |
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what is pipe relining |
pulling a new plastic line ino an existing pipe |
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what is pipe bursting |
the shattering of the existing pipe and pulling in of a new one |
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What is a caliper |
used to measure a trees diameter |
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Where do 90-95% of roots fall |
in the top 24 inches of the soil |
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How far do roots extend |
1 to 1 1/2 times the height of the tree |
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What does compaction do in a root system |
limits the growth of the roots |
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What are different types of tree protection |
orange plastic fencing, metal chain link fencing, and a 4x4 post and rail |
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what priorities should you follow in order when protecting a tree |
1st: the whole tree 2nd: the drip line
Last resort use layers of bark or net plywood |
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What three things should you plan for a dewatering system |
1. elevation of ground water 2. permeability of the soil 3. the limitations of the dewatering systems |
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What is a boring log |
a written record of information about the soil removed by drilling a hole into the earth |
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In a split spoon test why should you only use the last two numbers instead of three |
because of a general degree of error |
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Compaction is |
the soild density is increased by mechanically forcing soil particles together and removing air from the void spaces, this is done in hours |
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What does compaction do to the engineering properties of soil |
Increases the bearing strength, reduces compressibility, improves the volume change numbers, and reduces permeability |
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degree of compaction depends on |
soils physical and chemical properties, soils moisture content, compaction method, amount of compaction effort, thickness of the lift |
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What do well graded aggregates do better than poorly graded ones |
they compact more easily |
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What forces are used in compaction |
static weight, manipulation (kneading), impact, vibration |
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what is static weight |
constant weight on the soil |
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manipulation (kneading) |
when combined with pressure, most effective for cohesive plastic soils |
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impact |
uses blows at low frequency to compact the soil, which is very effective for plastic soils |
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vibration |
high frequency, effective in soils wit little cohesion, such as sand and gravel |
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What is consolidation |
increases the density of cohesive soils by expulsion of water from void spaces through 'squeezing'. this takes months to years to accomplish |
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What are proctor tests used to evaluate |
a soils moisture to density relation under a specified compaction effort |
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Modified Proctor Test |
uses a 10 lb. hammer falling 18 inches for five separate soil layers, also uses 25 blows, modified is 4 times the effort of standard with a MC between 5-12% |
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How are proctor tests plotted |
dry density vs. moisture content |
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As optimum moisture content decreases |
compaction effort increases |
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What are three in place density tests: |
liquid, sand, and nuclear |
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When to use a sheep's foot roller? |
On cohesive Soils |
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When to use a grid mesh roller |
on sand and gravel but at a higher speed than a sheeps foot roller |
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what is vibratory compaction |
either a walk behind or machice, used in non-cohesive soils |
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what is a smooth drum roller |
used for granular base materials, also used for asphalt bases |
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rubber tire/pneumatic roller |
used for damn construction and all soil types (least effective with sand) |
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What do you use in confined spaces |
a walk behind or attached to an excavator |
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What are the compaction operations (4 steps) |
select equipment determine quantity of water needed determine number of passes life: soil layer you put in |
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(SS) NAtural and chemical additives: |
mix the materials and then compact |
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Sodium and calcium chloride |
known for water holding properties, they increase the internal shear strength and the compressive strength of soils |
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What is calcium chloride capable of |
absorbing moisture from the air, whcih aids in dust control |
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Portland cement and asphalt |
can be used to bond soil particles together |
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Lime and calcium chloride |
improves the quality of clay, lime stabilizer can be used as well |
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what is the process for lime stabilizer |
mix, cure, remix, compact |
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In the blending of natural coarse aggregate and fine grained soils which is the binder |
the fine grained soils are the binder |
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Blending develops internal friction and cohesion which |
increases the load bearing capacity |
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What is vertical soil mixing |
cementing material mixed in using hollow stem auger and paddles which strengthens soft, wet cohesive soils |
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What is grouting stabilization |
grout is used to stabilize the soil in a drilled column |
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WHAT IS INJECTION STABILIZATION |
treating expansive clays by pressure injection of water, lime, and potassium chloride |
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What is ground/soil freezing |
improves soil stabilization, requires a refrigeration plant and temporary pipes, beneficial for excavation walls because it stops or slows ground water flow |
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What types of geo synthetics for stabilization and reinforcement |
fine mesh - geo textile, geo nets, and geo webs |
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What are geo synthetics are used for |
erosion control in areas exposed to water |
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What is a fabric mattress |
double layers of synthetic fabric and inner cells filled with concrete grout |
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What is dura base |
a temporary base for cranes and road beds |
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What does vibro compaction do |
increases the density for low cohesion soils such as sand and gravel, in this method a probe uses water and vibrates and clean granular soil is added around the probe |
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What is the hydraulic method (consolidation) |
drainage of soil by placing a weight on the soil to compress and hold soil in place removing water from clay, sand columns wick the water up and out of the soil |
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what does surveying determine |
the volume of soil to be added or removed from the site |
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Site work take offs are determined from three things |
plot plans, topo survey and work from total station |
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What does a dashed line signify in a topo survey |
existing elevations |
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what does a solid line mean in a topo survey |
proposed or finished elevations |
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What is site work clearing |
required to strip top soil 6-12" which is stockpiled or removed |
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What is cross sectional |
a simple cross view of an area (trench, roadway cut, or basement) |
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hat is the contour area (grid) |
easy method of calculating cut and fill for sites does not require sectional drawings or any complicated area formulas
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what is the 2 step process in contour area (grid) |
1. draw grid lines on site plan 2. mark readings of existing and proposed elevation, record and chart |
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What is the Unit area (avg. ht.) - borrow pit method |
calculate the difference at all intersection pts, and value pts. |
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What is balanced excavation |
where there is enough gill to level the site without removing or bringing in material |
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what is table topping |
cutting and filling to make flat space within the proposed building site |
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what is permeability |
the ability of water to move through soils |
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what does water content effect |
soil characteristics, which affects engineering application construction procedures and techniques |
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What is capillary rise |
how water moves up through the soil |
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In capillary action, the smaller the grains |
the less the void space which leads to higher capillary rise |
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what is frost heave |
the expansion of water when frozen |
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What does the vertical shift in frost heave do |
it is not uniform so it creates horizontal cracking of pavement walls and floors |
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what does frost heave require (2 things) |
requires cold, fine grained soils and a water supply |
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Temperature is not economical to control in frost heave so what can you control |
replace the fine grained with coarse which decreases water availability, and you can also starve the water supply |
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what is frost penetration |
when the ground freezes top down and moisture moves to the frozen area |
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the frozen material in frost penetration is dryer than moist soil so |
by crystallizing itself to the already frozen material makes it thicker |
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what is sheet eroision |
washing of top soil from land surface (greatest amount of soil loss) |
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what is rill eroision |
removal of soil by concentrated water through streamlets |
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When does detachment occur in rill erosion |
if the sediment in the flow is below the amount the load can transport and if the flow exceeds the soils resistance to ________. |
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As detachment in a rill continues rills become |
wider and deeper |
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What is gully erosion |
a larger version of rill erosion with an increase in water and velocity |
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Soil erosion increases during and after construction because |
removal of protective vegetation and the placement of impermeable surfaces that prevent water infiltration and increase runoff |
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What is sedimentation and when does it occur |
it follows erosion, sedimentation is the relocation of soil particles to other land bodies carried by rivers |
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What do wetlands provide |
natures filter for erosion and a habitat for wildlife |
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what is deposition |
when sediment settles in deepest and slowest moving waters |
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what is turbidity |
how clear the water is, a measure of how much particles are in water, great measure for water quality |
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what causes pollutant loading |
pesticides, herbicides and heavy metals |
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What is are the Best MAnagment practices |
vegetation, structural and managerial practices to limit water pollution control |
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BMP's (2 things) |
first: use erosion control methods second: sediment erosion control methods |
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What are the federal storm water regulations phases |
phase 1: construction disturbing 5+ acres phase 2: construction disturbing 1-5 acres |
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in permit coverage permitee shall |
not discharge into state water select control measures applicable to site maintain and operate soil control measures have a certified storm water operator to supervise inspect once a week and within 24 hours of a storm retain record for 3 years report to owner by keeping a log stabilize the site
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what are construction barriers |
limit construction traffic to specific areas |
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what is tree protection |
trees increase value of land, tree roots hold onto soil |
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where do you put a grass strip |
next to waterways and next to site boundaries |
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what is the purpose of tracking a dozer up and down the slope |
to prevent soil erosion |
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what is a buffer/filter strip |
grass strips filter water fertilizers and pesticides |
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what are sedimentation cones |
used to control sheet flow only |
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Where to not use spoil piles |
next to waterways or lakes |
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What is a filter fence: |
trench 6", backfill and stake on downside of water flow |
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remove build up fence if |
it is 1/3 to 1/2 height of fence |
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to control dust you should |
increase vegetation or dampen ground surface |
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what is hydro seeding |
fast dormant seed germinates as the snow melts |
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hen to apply mulch |
immediately after seeding in a uniform blanket |
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in sod what must you do to joints and where do you stake it |
stagger the joints and stake on the slopes |
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what is a temporary spoil pile |
limit chance of soil falling on workers in trench by placing it 2' from edge |
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where to store permanent spoil pile |
install in a stored distance away from excavation |
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When are pile foundations needed |
when upper soil is compressible when structure is subjected to horizontal forces soils are expansive and collapsible to resist uplifting forces to avoid bearing loss capacity due to shallow foundations and soil erosion
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how do piles carry loads |
end bearing due to loads being transferred through pile skin friction densifying the soil anchoring the structure from uplift
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Wood piles |
ADV: inexpensive DIS: max length of 60' and limited load capacity |
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Concrete (cast in place) piles |
Adv: size, depth, length are a needed |
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Precast concrete |
adv: high strength and resistance to decay dis: brittle, manufacturing and handling is complicated |
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Steel Piles |
adv: weld and shape dis: high cost and corrosion |
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Bulb Piles |
Driven and compacted concrete piles |
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Single vs group pile capacity |
too many piles is a problem |
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what are the pile load testing types |
static load and hydraulic jacking |
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describe sinking foundations |
can be anchored using concrete jacks can use grout to beef up foundation foundations are within substructure |
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Where do piers/caisson get support |
end bearing and skin friction |
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Cased vs uncased caissons: |
function of soil type and groundwater bentonite slurry: uncased or cohesive soil |
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advantages of piers/caissons over precast |
no driving damage to pile can be poured to exact length |
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adv of piers/caissons over driven piles |
less ground vibration and damage inspect subsoil to determine base quality equipment is light as opposed to pile drivers |
