Transcript shallow surface compaction

SHALLOW SURFACE
COMPACTION
DONE BY :
Abdulmajeed alsultan
1
Outline
1.
2.
3.
4.
Soil Improvement
Compaction
Field Compaction Equipment
Field Compaction Testing
2
Soil Improvement
3
Methods for Soil Improvement
Ground
Reinforcement
•
•
•
•
•
•
•
•
•
•
•
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
Ground
Improvement
•
•
•
•
•
•
Drainage/Surcharge
Electro-osmosis
Compaction grouting
Blasting
Surface Compaction
Deep Dynamic
Compaction
Ground
Treatment
•
•
•
•
•
•
Soil Cement
Lime Admixtures
Flyash
Dewatering
Heating/Freezing
Vitrification
4
Compaction
5
Objectives of compaction
Objectives:
(1)
(2)
(3)
(4)
(5)
Decrease future settlements
Increase shear strength
Decrease permeability
Control swelling and contraction
Increases slope stability of embankments
6
Compaction
What is different between compaction and Consolidation ?
Compaction
Densification of soil by removing air from the voids.
Consolidation
Densification of soil by removing water from the voids.
7
Types of Compaction
Types of Compaction :
There are four types of compaction effort on soil :
• Vibration
• Impact
• Kneading
• Pressure
SATURATED SOIL NOT COMPACTABLE
8
Field Compaction Equipment
9
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
10
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.
11
Equipment
Sheepsfoot rollers
• 8% ~ 12 % coverage
• Contact pressure is from 1400 to
7000 kPa.
• Compactive effort: static weight
and kneading.
12
Equipment
Sheepsfoot rollers
• Suitable for :
– fine grained soils
– sands and gravels (with >20% fines)
• Unsuitable for:
– very coarse soils
– uniform gravels
13
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.
14
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
15
Equipment
Vibrating drum on smooth-wheel roller
• Compactive effort: static weight
and vibration.
• Suitable for granular soils
16
Equipment
Vibrating Plate :
• Suitable for :
– most soils with low to moderate
fines content
• Unsuitable for:
– large volume work
– wet clayey soils
17
Equipment
Power Rammer :
• Also called a trench tamper
• Suitable for :
– trench back-fill
– work in confined areas
• Unsuitable for:
– large volume work
18
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
19
Field Compaction
Testing
20
Field Density Testing Method
Field Density Testing Method
Sand Cone
Advantages
Disadvantages
Errors
Cost
Balloon Dens meter
Shelby Tube
Nuclear Gauge
• 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)
• 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
• 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
• Low
• Moderate
• Low
• High
21