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Published byArron Rodney Hardy Modified over 8 years ago
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Soil and Rock Soil and rock are the principle components of many construction projects. Knowledge of their properties, characteristics, and behavior is important to those associated with the design or construction of projects.
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Soil and Rock
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Soil and Rock
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Soil and Rock Steel and concrete are construction materials that are basically homogeneous in composition. As such, their behavior can be predicted. Soil and rock are just the opposite. By nature they are heterogeneous. In their natural state, they are rarely uniform.
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Soil and Rock Soil and rock are heterogeneous. They are rarely uniform and work processes are developed by comparison to a similar type material with which previous experience has been gained. To accomplish this, soil and rock types must be classified.
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GRADATION Soil gradation is the distribution, in percent (%) by weight, of individual particle sizes.
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SOIL TYPES ORGANIC SOILS Will usually have to remove before building.
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SOIL TYPES NON-COHESIVE Bulky shaped soil grains
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SOIL TYPES COHESIVE Platy shaped soil grains Small grained
#200 Mesh sieve
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SOIL LIMITS Atterburg Limits LL - Liquid limit PL - Plastic limit PI - Plasticity Index
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SOIL LIMITS Stages of Consistency Moisture content decreasing
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SOIL LIMITS LL - Liquid limit
is the water content of a soil when it passes from the plastic to liquid state.
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SOIL LIMITS LL - Liquid limit
Non-cohesive or sandy soils have low LLs -- less than 20. Clay soils have LLs ranging from 20 to 100.
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SOIL LIMITS PL - Liquid limit
is the lowest water content at which a soil remains plastic. 1/8 inch diameter thread
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SOIL LIMITS PI - Plastic Index PI = LL - PL
The higher the PI the more clay that is present in the soil.
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Volumetric Measure Bank cubic yards (bcy) Loose cubic yards (lcy)
Compacted cubic yards (ccy) lcy ccy bcy
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COMPACTION Each soil has its particular optimum moisture content (OMC) at which a corresponding maximum density can be obtained for a given amount of compactive input energy.
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COMPACTION
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COMPACTION PROCTOR TEST Standard Proctor or AASHTO T-99
Soil sample 1/30 cubic foot 3 layers
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COMPACTION PROCTOR TEST Modified Proctor or AASHTO T-180
Soil sample 1/30 cubic foot 5 layers
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COMPACTION SPECIFICATIONS
Typically specifications give an acceptable range of water content, OMC ± 2% for example.
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COMPACTION SPECIFICATIONS
The specification also sets a minimum density, 95% of max. dry density for a specific test 126.4
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Must work in the box.
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Soil Weight-Volume Relationships
Equ. 4.1 Equ. 4.2 Equ. 4.3
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Water Content =
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Water Content = = 0.18 or 18%
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Soil Weight-Volume Relationships
Dry weight is related to unit weight by water content, and when you move rock and dirt the only thing that stays constant is the weight of the solid particles.
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Soil Weight-Volume Relationships
When you move rock and dirt the only thing that stays constant is the weight of the solid particles.
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unit weight () of 94.3 pcf water content () of 8%.
EXERCISE The excavated material has a unit weight () of pcf water content () of 8%.
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dry unit weight (d) of 114 pcf water content () of 12%.
EXERCISE The embankment will be compacted to dry unit weight (d) of 114 pcf water content () of 12%.
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How many cubic yards of excavation will be required to construct the
EXERCISE The net section of the embankment is 113,000 cy. How many cubic yards of excavation will be required to construct the embankment?
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EXERCISE As material is moved from the excavation
to the compacted fill the only constant is the weight of the solid particles (d).
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EXERCISE Step 1 Weight of the solid particles which make up the embankment (fill). a dry unit weight (d) of 114 pcf 113,000 cy embankment Conversion factor cy to ft3
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EXERCISE Step 2 Use relationship d - to calculate the dry unit weight of the excavated material. a unit weight () of 94.3 pcf a water content () of 8% d = pcf
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EXERCISE Step 3 Calculate the weight of the solid particles which make up the excavation (cut).
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The weights must be equal therefore:
EXERCISE Step 4 The weights must be equal therefore: = Conversion factors cancel out.
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excavated material required
EXERCISE Step 4 The weights must be equal therefore: x = x = 147,535 cy excavated material required
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EXERCISE Check the water requirements.
Will a water truck be needed on the job or will it be necessary to dry the material?
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Water content () is? x d = weight of water/cf
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Step 1 Water from Cut Vol. Cut d conversion factor ()
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Step 1 Water from Cut = 27,825,120 lb water
delivered with the borrow material
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Step 2 Water needed at the Fill
Vol. Emb d conversion factor ()
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Step 2 Water needed at the Fill
= 41,737,680 lb water needed at the fill
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Step 3 Water Deficiency Needed at the fill 41,737,680 lb
Delivered w/ cut 27,825,120 lb Water deficiency 13,912,560 lb
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PE 2 Step 4 Convert to Gallons
Water deficiency 13,912,560 lb Water weights lb/gal Need to add 1,670,175 gallons
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11.3 gal/cy Step 5 Gallons per cy Need Water deficiency 1,670,175 gal
Volume of cut 147,535 cy Need 11.3 gal/cy
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Adding Water Using sprinklers to add moisture to a foundation fill.
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Reducing Moisture Disking a heavy clay fill to reduce moisture.
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