1. CTC-375 Construction Methods
Earthwork

2. Get SUNYIT email account

3. Construction Order There is an order to all projects
What activities get done first
What activities need to be done in a specific order
What activities can be done at any point in time

4. Start at beginning Earthwork
Moving rock or soil from one location to another
Processing it to meet location, elevation, density moisture content, etc
Efficient earthwork requires: accurate estimating of work quantities and conditions, proper equipment, competent job mangement

5. Equip Selection
Proper equipment has major impact on efficiency and profitablility
Can equipment perform required work
Also look at profitablility, other uses for equipment, return on investment, availability of parts and services, effect of downtime on other construction equip

6. Equipment planning Need to plan to effectively use equipment
Production of equipment
Production = Volume per cycle/cycles per hour
Cycles per hour is based on efficiency of equip
Swing angle and elevation to truck bed
Soil hardness and Soil type
Room to manuever

7. Equipment planning
Cost per production unit = equip cost per working hour/equip production per hour
Table 2-1 show efficiencies

8. Soil And Rock General Soil Characteristics
Trafficability – ability of soil to support weight of vehicles under repeated traffic
Controls traffic on unimproved access roads
Also gives measure of how earthmoving equip will operate
Primarily function of moisture conditions and soil type
Loadability – how difficult to excavate and haul a soil
Granular – high
Compact cohesive - low

9. Soil And Rock Unit Soil Weight Pounds /cy
Depends on soil type, moisture content, degree of compaction
Relation between soil weight and bearing capacity
So soil weight is used as a measure of compaction
Soil weight is also a factor in hauling

10. Soil And Rock Moisture Content(%) = (moist wt – dry wt)/dry wt X 100
Soil sample 120#
Dry weight 100#
MC = ( )/100X100 = 20%

11. Soil ID Boulders Cobbles – over 3” diameter Gravel 1/4” – 3” diameter
Sand 0.7mm (200 sieve) – ¼” diameter
Silt – 0.7 mm
Clay less than 0.002mm
Organic Matter decaying organic matter
Soils classified using these types

12. Soil Classification Systems
Unified System
All material 3’’+ removed
Separates soils into two main groups- Fine grained and coarse grained
Table 2-2, Figure 2-1
AASHTO System
7 classes of soil
Based on suitability of soil for subgrade
Table 2-3
Table 2-4

13. Soil Volume Change Characteristics
Soil Conditions
Bank – material in natural state before disturbance – Bank cubic yard
Loose – material that has been excavated or loaded loose cubic yard
Compacted – material after compaction compacted cubic yard

14. Soil Volume Change Characteristics
Swell
Soil increases in volume when it is excavated
Soil grains are loosened and air fills voids
So 1 unit of soil in bank is smaller than the soil once it is excavated
Swell(%) = ((weight/bank vol)/(weight/loose vol)-1)X100
Soil wt = 2800#/cy in bank
Soil wt = 2000#/cy loose
Swell = ((2800/2000)-1)X100 = 40%

15. Soil Volume Change Characteristics
Shrinkage
Soil decreases in volume when it is compacted
Air is forced out of soil
So 1 unit of soil compacted is smaller than the soil in the bank or once it is excavated
Shrinkage(%) = (1-(weight/bank vol)/(weight/compacted vol))X100
Soil wt = 2800#/cy in bank
Soil wt = 3500#/cy compacted
Swell = (1-(2800/3500))X100 = 20%

16. Soil Volume Change Characteristics
Load and Shrinkage Factors
Need a common unit of measure for earthwork (get rid of calculations )
Can use any of the three measures
Called pay measure in contract
Load factor = 1/(1+swell)
Shrinkage factor = 1- shrinkage
Table 2-5

17. Spoil Banks Material removed from excavation
Longer than wide – spoil bank – triangular x section
Conical – spoil pile
To determine the size of the bank or pile need swell and angle of repose for soil
Angle of repose = angle that soil on side of bank naturally form
Varies with moisture content and type
Table 2-6

18. Spoil Banks Spoil bank Vol = X-sect area x length
B = (4V/(L x tan R))^1/2
H = (B x tan R)/2
B – base width
H height
L length
R angle of repose
V volume

19. Example
You have to store 30,000 BCY of soil in an area no wider than 80 feet
How long is the spoil bank?
Swell = 25%

20. Spoil Banks Spoil pile Vol = 1/3 p(D/2)^2 X H D = (7.64V/tan R)^1/3
H = D/2 x tan R
D – diameter of base
H height
R angle of repose
V volume

21. Estimating earthwork 3 types of excavations Roadways Small pit Trench
Large areas
Roadways
Find cut and fill using cross sections
Mass diagram

22. Estimating earthwork Pit Excavations Area X average depth
Depending on size and ground may break into several geometric shapes to get volume
Give bank volume

23. Estimating earthwork Trench Excavations V = x sectional area X length
Take x sections every 50 feet and compute volumes between x sections

24. Estimating earthwork
Large Areas
Use a grid to find volume