Date post: | 07-Aug-2015 |
Category: |
Documents |
Upload: | engineer-imtiaz-rehman |
View: | 52 times |
Download: | 0 times |
SOILCOMPACTIONImtiaz Ur Rehman (B.Sc. Civil Engineering)
COMPACTION - Densification of soil by removing air voids using mechanical equipment
Why Soil Compaction? 1- Increase Soil
Strength 2- Reduce Soil
Settlement 3- Reduce Soil
Permeability 4- Reduce Frost
Damage 5- Reduce Erosion
Damage
3
COMPACTION Vs CONSOLIDATIONCompaction – expelling air from the void space
Consolidation – extrusion of water
Solids
Water
Air
Solids
Water
Air
Compressedsoil
Load
SoilMatrix
gsoil (1) = WT1
VT1gsoil (2) =
WT1
VT2
gsoil (2) > gsoil (1)
5
Factors Affecting Soil Compaction1. Moisture content2. Compaction effort
Compaction energy per unit volume (function of number of blows per layer)
For the stand proctor test: 12,400 ft-lb/ft3
For the modified proctor test: 56,000 ft-lb/ft3
3. Type of soilGrain size distributionSpecific gravity of solidsType and amount of clay materials
6
What does water do for compaction?
• Lubricant• Too much water lesser density• Optimum moisture content
(=maximum dry unit weight) best compaction
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
10 11 12 13 14 15 16 17 18 19 20 21 22 23
gdry max
OptimumWaterContent
7
What does Compaction Effort do?
8
What is role of Soil Type?
9
More Useful Information
10
Checking Soil Density in the Field
1- Sand Replacement Method2- Rubber Balloon Method3- Nuclear Density Gauge Method4- Core Cutter Method
11
A small hole (6" x 6" deep) is dug in the compacted material to be tested. The soil is removed and weighed, then dried and weighed again to determine its moisture content. A soil's moisture is figured as a percentage. The specific volume of the hole is determined by filling it with calibrated dry sand from a jar and cone device. The dry weight of the soil removed is divided by the volume of sand needed to fill the hole. This gives us the density of the compacted soil in lbs per cubic foot. This density is compared to the maximum Proctor density obtained earlier, which gives us the relative density of the soil that was just compacted.
1- Sand Replacement Method
12
Sand Replacement Method
13
2- Rubber Balloon Method
14
3- Nuclear Density Meter Method
15
PROBLEMS IN COMPACTION EVALUATION
16
PROBLEMS IN COMPACTION EVALUATION
17
THANKS