soil compaction topic i. success of embankment proper preparation of foundation. use of suitable...
TRANSCRIPT
Soil Compaction
Topic I
Topic I
Success of Embankment
• Proper preparation of foundation.
• Use of suitable materials.
• Proper placing working and compacting of materials.
Topic I
Proper Preparation of Foundation
• Clear and grub area• Cut vegetation• Remove perishable material• Strip and stockpile• Compact area
Topic I
Suitable Materials
• Rock• Sand• Silt• Clay• See Standard specifications list
Topic I
Unsuitable Materials
• Organic soils should not be used as embankment or subgrade material.
Topic I
Proper Placement and Compaction
• Placing layers
• Placing in marsh
• Placing rock
Topic I
Placing Layers
• The maximum thickness of a layer should not exceed 8 inches loosely placed.
• 8 inch lifts
Topic I
Placing Layers
• Compact each layer
• Level each layer
• Parallel
Topic I
Placing in Marsh
• Typically in wet marsh excavations WisDOT allows for marsh backfill to be end dumped into excavation and “surged” down into the excavation with a bulldozer until above water level.
Topic I
Topic I
Topic I
Topic I
Placing Rock
• No end dumping• Bulldozed or shoved into position• Various sizes• When placing rock all voids must be filled with
finer material.
Topic I
Topic I
Principles of Compaction
1. Decrease future settlements
2. Increase shear strength
3. Decrease permeability
4. Increase stability
Topic I
Not Achieving Compaction?Solutions
• Increase compaction effort–Compaction equipment
• Change soil moisture content–Optimum moisture content
Topic I
Figure 1: Compaction Equipment
Topic I
Figure 1: Compaction Equipment
Topic I
Static smooth drum roller works well for sealing subgrades after the days grading operations are complete.
Doesn’t work well on clay soils.
Standard Compaction
• Embankment compaction
Topic I
Special Compaction
• Density tests–Sand Cone Method–Nuclear Method
• Minimum frequency
Topic I
Moisture Control
• Proper moisture conditions are essential for the efficient compaction of earth embankments. Satisfactory moisture conditions almost always are specified in relation to the optimum moisture content for a standard laboratory compaction test.
Topic I
Moisture Control
• Discs for wet cohesive soils
• Blade crown on surface
• Mixed
Topic I
Documentation- Cut sections
• Excavated proper grade• Frost susceptible materials• Compaction• EBS• Drainage• Proper disposal
Topic I
Documentation- Embankments
• Preparation of foundation
• Soils utilized
• Placing and compacting of materials
Topic I
Documentation-Entries
• Soil type• Moisture content• Layer thickness• Drying or wetting• Routing pattern
Topic I
Earthwork Equipment
• Hauling• Leveling• Aerating• Compacting
Topic I
Figure 2: Track Dozer
Topic I
Track Dozer
• Track Dozers are not to be used as compaction equipment.
• Used to level lifts of fill.
Topic I
Subgrade Care
Topic I
Topic I
Topic I
Figure 3:Disc Drying
Topic I
Disc Drying
• Drying of wet soils is necessary and can be accomplished by using graders, discs or harrows.
• Aeration of the soil• Necessary for compaction
Topic I
Figure 4: Rubber Tire Dozer
Topic I
Rubber Tire Dozer/Scrapers
• Hauling, Leveling and Compacting
Topic I
Figure 5: Sheepsfoot Imprint
Topic I
Sheepsfoot Imprint
• Optimum moisture–High volume compaction
• Lower water content–Increase soil surface
• Cohesive and semi-cohesive soils
Topic I
Figure 5: Motor-Grader
Topic I
Motor-Grader
• Aerates and levels
• Takes out ruts
• Not for compaction
Topic I
Figure 6: Solid Subgrade
Topic I
Solid Subgrade
• Keeps subgrade bladed up.• Keeps ruts out.
Topic I
Figure 7: Excessive Rutting
Topic I
Topic I
Excessive Rutting
• Material too wet• Solutions:
–Motor-grader– Tractor–Disc
Topic I
Figure 8: Embankment construction
Topic I
Embankment Construction Equipment
• Dozer
• Tamping Roller
• Motor-Grader
Topic I
Figure 9: Dumping and Leveling
Topic I
Dumping and Leveling
• Firm and unyielding support.• Prior to first lift.
Topic I
Figure 10: Tamping Virbratory Roller
Topic I
Tamping Vibratory Roller
• “Dry”, bony material doesn’t stick.
Topic I
Figure 11: Excellent Material
Topic I
Excellent Material
• Dry and granular• Some rock• Imprints stand out• Not common in WI
Topic I
Figure 12: Good Conditions
Topic I
Good Conditions
• Back tire of grader is not sinking.
Topic I
Figure 13: Scraper End Dumping
Topic I
Scraper End Dumping
• Pushed into wet area.–Granular material
• Seal first lift• Don’t trap unstable soil in embankment.
Topic I