Team Assignments
Team Assignments
CE403 Construction Methodology
Earthwork Fundamentals
4
LEARNING OBJECTIVES
Define the common Soil PropertiesSoil Properties and how to determine each.
Define Soil-Volume ChangesSoil-Volume Changes that occur during earthmoving operations.
Define SwellSwell, and ShrinkageShrinkage, and how to determine the LoadLoad & Shrinkage FactorsShrinkage Factors.
Define Angle of ReposeAngle of Repose for common Soil Materials. Describe the two common Soil Classification Soil Classification
SystemsSystems and Basic DefinitionsBasic Definitions.
5
Soil Properties
Any mass of soil consists of solid particles with voids in between.
Soil solids are small grains of different minerals
Voids can be filled with either water or air
6
Soil Properties
Total volume of the soil mass, Vt, consists of volume of soil solids, Vs, and the volume of voids, Vv
The volume of the Voids, Vv, consists of volume of water, Vw, and the volume of air, Va
7
Soil Properties
We can schematically represent these three phases in a phase diagram.
Soil
H2O
Air
MT
MS
VT
VV
VS
VA
VW
MW
MA
= 0
Volume Mass
8
Soil Properties
Three volumetric ratios1. Void ratio:
Normally expressed as a decimal Max range of e is between 0 and infinity Typical values: Sand (0.4 to 1.0); Clays (0.3 to 1.5)
S
VV
V = e
9
Soil Properties
Three volumetric ratios2. Porosity
Normally expressed as a decimal Max range of n is between 0 and 100%
(%)100V
V = n
T
V x
10
Soil Properties
Three volumetric ratios3. Degree of Saturation
The degree of saturation tells us what percentage of the total volume of voids contains water
If soil is completely dry, S=0. If the pores are completely filled with water, S=100%
(%)100V
V = S
V
W x
11
Soil Properties
Mass relationships– Water (moisture) content:
Can range from zero (dry soil) to several hundred percent Water content for most soils is well under 100%, although it can
range up to 500% or higher in some marine and organic soils
x100(%)M
M = ω
S
W
12
Soil Properties
Mass relationships– Total density:
Magnitude will depend on amount of water in the voids and density of the mineral grains
Typical values for most soils range from 1000 to 2400 kg/m3
VtMwMs
T
T V
M = ρ
13
Soil Properties
Mass relationships– Solid density:
Typical values for most soils range from 2500 to 2800 kg/m3 (2.65 Mg/m3)
– Dry Density:
V
M = ρ
S
Ss
V
M = ρy Dry Densit
T
SDRY
14
Soil Properties
Mass relationships– Density of Water:
The density of water varies slightly, depending on the temperature.
For most engineering work, it is sufficiently accurate to estimate pw=1000kg/m3=62.4lb/ft3
Vw
M = ρ ww
15
Common Soil Properties
Soil
H2O
Air
MT
MS
VT
VV
VS
VA
VW
MW
MA
= 0
16
Example Problem
Given the Following:
Vs=65 cm3, Vw=25 cm3, Va=10cm3
Ms = 175g, Mw=25g
Find:
Total Density, dry density, moisture content, void ratio, saturation, and porosity of the soil sample
18
Soil Volume-Change Characteristics
Bank VolumeBank Volume - (BCYBCY) – Material is in natural state before disturbance
Loose VolumeLoose Volume - (LCYLCY) – Material has been excavated or loaded.
Compacted VolumeCompacted Volume - (CCYCCY) – Material after compaction.
19
Soil Volume-Change Characteristics
21
Swell
A soil increases in volume when it is excavated because the soil grains are loosened during excavation and air fills the void spaces created.
100%1 VolumeseWeight/Loo
VolumekWeight/BanSwell(%)
22
Shrinkage
When soil is compacted, air is forced out of void spaces.
The soil will occupy less volume than it did under either bank or loose conditions.
100% VolumepactedWeight/Com
VolumekWeight/Ban1
(%) Shrinkage
23
Load Factor
Swell%1
1Factor Load
Volumek Unit Weight/Ban
Volume Unit seWeight/LooFactor Load
24
Shrinkage Factor
Shrinkage%1 Factor Shrinkage
Volume Unit pactedWeight/Com
Volumek Unit Weight/BanFactor Shrinkage
25
Soil Weight & Volume Change Characteristics
Unit Weight lb/cuyd Loose Bank Compacted Clay 2,310 3,500 3,750 Common Earth 2,480 3,100 3,450 Rock Blasted 3,060 4,600 3,550 Sand & Gravel 2,860 3,200 3,650
Swell % Shrinkage % Load
Factor Shrinkage
Factor Clay 10 20 0.77 0.80 Common Earth 25 10 0.80 0.90 Rock Blasted 50 -30 0.67 1.30 Sand & Gravel 12 12 0.89 0.88
27
Load & Shrinkage Example Problem
A soil weighs 1,960 lb/LCY, 2,800 lb/BCY and 3,500 lb/CCY.
b. How many BCY & CCY are contained in 1,000,000 LCY?Bank Volume
1,000,000 LCY x 1,960/2,800(BCY/LCY) == 1,000,000 LCY x 0.70(BCY/LCY) = 700,000 BCYCompacted Volume
1,000,000 LCY x 1,960/3,500 (CCY/LCY)= or= 700,000 BCY x 0.80 (CCY/BCY) = 560,000 CCY
28
Unified Soil Classification System
Two Letter System– Symbols to represent soil type:
Symbol Soil TypeG GravelS SandM SiltC ClayPt Highly organic soil and peat.
– Symbols to represent index propertiesW Well-graded (for grain-size distribution)P Poorly-graded (for grain-size distribution)L Low to medium plasticityH High plasticity
29
Angle of Repose
The angle that the sides of a spoil bank or pile naturally form with the horizontal when the excavated soil is dumped onto a pile.
The angle varies with the soil’s physical characteristics and its moisture content.
30
Materials & Angle of Repose
Clay 35° Common Earth, Dry 32° Common Earth, Moist 37° Gravel 35° Sand, Dry 25° Sand, Moist 37°
31
Spoil Pile
Dumped from a single fixed point
Volume =1/3 Base Area x HeightVolume =1/3 Base Area x Height
H
D
CF Volume,PileV
degRepose, of AngleR
ftBase, Pile of Diameter =D
ft Height, PileH
tan(R)2
DH
tan(R)
7.64VD
1/3
32
Soil Identification & Classification
GRAVEL < 3” to > 1/4” diam. SAND < 1/4” to > 200 Sieve
SILT < 200 Sieve to > 0.002 mm
CLAY < 0.002 mm ORGANIC MATERIAL
Contains Decomposed Vegitatable Matter.
33
34
Basic Definitions
The liquid limitliquid limit (LL) is the water content (%) at which the soil will just start to flow when subjected to standard shaking test. (Casagrande Test)
The plastic limitplastic limit is the moisture content (%) at which the soil just begins to crumble when rolled into a thread 1/4” in diameter.
The plastic indexplastic index is the numerical difference between the liquid and plastic limits and represents the range in moisture content over which the soil remains plastic.
35
36
Unified Soil Classification System
Two Letter System– Symbols to represent soil type:
Symbol Soil TypeG GravelS SandM SiltC ClayPt Highly organic soil and peat.
– Symbols to represent index propertiesW Well-graded (for grain-size distribution)P Poorly-graded (for grain-size distribution)L Low to medium plasticityH High plasticity
37
38
AASHTO Soil Classification System
American Association of State Highway and American Association of State Highway and Transportation OfficialsTransportation Officials
A-1 through A-7 Table 2-3, Page 25.
39
40
Construction Characteristics of Soils
1. Drainage
2. Construction Workability
3. Suitability for Subgrade
4. Suitability for Surfacing
41
42