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SHALLOW SURFACE COMPACTION

DONE BY :

Abdulmajeed alsultan

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Outline

1. Soil Improvement

2. Compaction

3. Field Compaction Equipment

4. Field Compaction Testing

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Soil Improvement

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Methods for Soil Improvement

Ground Reinforcement

Ground Improvement

Ground Treatment

• Stone Columns• Soil Nails• Deep Soil Nailing• Micropiles (Mini-piles)• Jet Grouting• Ground Anchors• Geosynthetics• Fiber Reinforcement• Lime Columns• Vibro-Concrete Column• Mechanically Stabilized

Earth• Biotechnical

• Drainage/Surcharge• Electro-osmosis• Compaction grouting• Blasting• Surface Compaction• Deep Dynamic

Compaction

• Soil Cement• Lime Admixtures• Flyash• Dewatering• Heating/Freezing• Vitrification

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Compaction

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Objectives of compaction

Objectives:(1) Decrease future settlements

(2) Increase shear strength

(3) Decrease permeability

(4) Control swelling and contraction

(5) Increases slope stability of embankments

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Compaction

What is different between compaction and Consolidation ?

CompactionDensification of soil by removing air from the voids.

ConsolidationDensification of soil by removing water from the voids.

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Types of Compaction

Types of Compaction :There are four types of compaction effort on soil : • Vibration • Impact • Kneading • Pressure

SATURATED SOIL NOT COMPACTABLE

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Field Compaction Equipment

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Equipment

Smooth-wheel roller (drum)

• 100% coverage under the wheel

• Contact pressure up to 400 kPa

• Can be used on all soil types except for rocky soils

• Compactive effort : static weight

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Equipment

Pneumatic (or rubber-tired) roller

• 80% coverage under the wheel

• Contact pressure up to 700 kPa

• 7 to 13 wheels are arranged in two rows.

• Can be used for both granular and fine-grained soils.

• Compactive effort : static weight and kneading.

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Equipment

Sheepsfoot rollers

• 8% ~ 12 % coverage

• Contact pressure is from 1400 to 7000 kPa.

• Compactive effort: static weight and kneading.

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Equipment

Sheepsfoot rollers

• Suitable for :

– fine grained soils

– sands and gravels (with >20% fines)

• Unsuitable for:

– very coarse soils

– uniform gravels

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Equipment

Mesh (or grid pattern) roller

• 50% coverage

• Masses range from 5-12 Tones

• Contact pressure is from 1400 to 6200 kPa

• Compactive effort: static weight and vibration.

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Equipment

Mesh (or grid pattern) roller

• Suitable for: – well-graded sands – soft rocks – stony soils with fine fractions

• Unsuitable for: – uniform sands – Silty sands – Very soft clays

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Equipment

Vibrating drum on smooth-wheel roller

• Compactive effort: static weight and vibration.

• Suitable for granular soils

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Equipment

Vibrating Plate :

• Suitable for : – most soils with low to moderate fines content

• Unsuitable for: – large volume work – wet clayey soils

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Equipment

Power Rammer :

• Also called a trench tamper

• Suitable for : – trench back-fill – work in confined areas

• Unsuitable for: – large volume work

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Variables-Vibratory Compaction

There are many variables which control the vibratory compaction or densification of soils.

• Characteristics of the compactor: (1) Mass, size (2) Operating frequency and frequency range

• Characteristics of the soil: (1) Initial density (2) Grain size and shape (3) Water content

• Construction procedures: (1) Number of passes of the roller (2) Lift thickness (3) Frequency of operation vibrator (4) Towing speed

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Field Compaction Testing

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Field Density Testing Method

Field Density Testing Method

 

Sand Cone Balloon Dens meter Shelby Tube Nuclear Gauge

Advantages• Large sample• Accurate

• Large sample• Direct reading   obtained  • Open graded    material

• Fast• Deep sample• Under pipe haunches

• Fast• Easy to redo• More tests (statistical reliability)

Disadvantages 

• Many steps• Large area required• Slow• Halt Equipment• Tempting to accept flukes

• Slow• Balloon breakage• Awkward

• Small Sample• No gravel• Sample not always retained

• No sample• Radiation• Moisture suspect• Encourages amateurs

Errors

• Void under plate• Sand bulking• Sand compacted• Soil pumping

• Surface not level• Soil pumping• Void under plate

• Overdrive• Rocks in path• Plastic soil

• Miscalibrated• Rocks in path• Surface prep required• Backscatter

Cost • Low • Moderate • Low • High