• Example
• Compacting Soils
• Example

ÑwFÑw2/10/1995 11:17:48first part of notes for class 4202class notes

Natural:bank measure (bcy)

undisturbed earth

Excavated:loose measure (lcy)

truck loaded or as-dumped

Relocated: compacted measure (ccy)

incorporated in project

Swell % varies significantly by category (see Table 5-1)

A contractoral pay volume may be bcy, lcy or ccy.

Load factor (lf) converts between bcy & lcy.

Shrinkage factor (sf) converts bcy & ccy.

Example

Example: Desire to place 18,000 cy compacted fill.

Soil used weighs:

• insitu 120 lb/cf --> bcy

• loose 96 lb/cf

• compacted 128 lb/cf

How many bcy required?

How many truck loads from borrow pit for 16 cy trucks?

% swell is what?

% shrinkage is what?

What should be the best basis for payment?

~could be bcy, lcy or ccy

Truck capacity

~struck filled level with top

~heaped filled to heaping

Compacting Soils

Specification methods - i.e., what is specified

~construction method only

~end result only (performance type spec)

~combining of method & end result generally is not desirable

Compaction methods

~kneading action (manipulation) (pgs 274 - 292, textbook)

~static weight (pressure)

~vibration (pgs 282, 283, 286, textbook)

~impact

~explosives

Compaction equipment (pgs 274-292, textbook)

~tamping foot roller: sheep’s-foot, pads, grid or mesh

~smooth-wheel roller

~pneumatic-tired roller (wobble-wheel)

~vibrating rollers: above versions that vibrate

~plates/shoes - manual

~impact rams

~vibratory probes

Soil stabilization methods (see pgs. 294-295, textbook)

Compaction is by lifts

Optimum moisture is essential(The percent of water, which corresponds to the maximum dry density)

Equipment combinations are frequently used

Earthwork is performed in series of steps

~loosen earth

~excavate - borrow pit

~loading

~hauling

~dumping - spreading - rough grading - stabilization - compaction

~finishing - spreading

Spreading equipment

~scraper (pg 145, 146, textbook)

~bulldozer (pg 97, textbook)

~motor grader

~automatic trimmer - finish grading

Spreading production estimating (linear or area basis)

~linear basis (most common)

~time required to complete the job

Example

Example: Reshape & level 12 miles of gravel road with 5 passes as follows:

• 1st & 2nd passes @ 3.0 mph;

• 3rd & 4th passes @ 4.0 mph;

• 5th pass @ 5.5 mph.

~assume 50 productive minutes per hour. The average speed is

Equipment Production Rate

Example:Excavate a canal by removing 350,000 cy within 60 calendar days. Calculate pertinent production rates.

~Assume 40 hr/wk:

•Is this practical to use when estimating the job?

~Assume lost time - weather 15% & contingency 5%:

•15% + 5% = 20% loss, implies 0.8 effective

•Then what about the human factor?

~ Assume lost personal time - drinks, toilet, talking, etc.:

•Experience 50 minutes production each hour

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