1. Foundations Excavations
ARCH 330
Fall 2008

2. Yes, I was a stud.

3. The Function of a Foundation

4. Foundations
Foundation Engineering- Evaluating the ability to support a given structural load and designing the substructure or transition member needed to support the construction. To transfer the structural loads safely into the ground.
This means dealing with forces and soil pressures. The need for deep excavations.

5. Foundations Spread Footings Driven Piles Caissons or Drilled Shafts
Proper compaction under the footing
Driven Piles
Types of piles
Wood
Concrete
Steel
Composite
-Pile Drivers
Drop Hammer
Mechanical- Hydraulic, diesel, steam
Vibratory
Caissons or Drilled Shafts
Cofferdams

6. Review Plans & Specifications
Consistency with geotechnical report
Reduce confusion during construction
Without Differing Site Conditions clause contractor responsible
Read the report in response to what is underground.
Understand prescribed method, consistency with soils report
Site Investigations
Environmental restrictions
Site conditions at each and every location
The report has pertinent information- follow it.
Compaction testing
Understanding moisture content
Proper proctor

7. Geotechnical Studies Soils Report
Buildings
Retaining Walls
Bridges
Roadways
Landslides
Forensic Investigations

8. Importance of Geotechnical Studies
Provide efficient foundations systems
Improve bid accuracy
Reduce change orders
Reduce long term problems

9. Geotechnical/Soils Reports Recommendations
Suitability of on site soil for structural fill
Bearing capacity
Foundation type
Lateral earth pressures
Pavements
Drainage
Seismic

10. Steps for Geotechnical Study
Explore site conditions
Perform lab testing
Perform engineering analysis
Prepare report
Assist with plans and specifications
Construction observations

11. Soil Report Borings or test pits To lab for: Moisture content
Gradations
Proctor test
Consolidation, direct shear, triaxial

12. Pile & Pile Driving Site Investigation Type & weight of structure
Soil properties
Depth of stratum
Variations of stratum depth
Availability of piling type
Availability of pile driver
Availability of experience in driving pile

13. Pile & Pile Driving (Site Investigation cont)
Comparative placement cost
EPA & OSHA regulations
Depth of excavation for placement of equipment ie building footing
Location of piling ie river, lake, ocean
Noise & Vibration
Adjacent structures

14. Pile & Pile Driving Piling Types Wood Pile Precast Concrete Pile
Steel H-Pile
Steel Pipe Pile
Composite Piles
(Please review page )

15. Pile & Pile Driving Pile Caps & Grade Beams
Piles are clustered then caped
Number of piles per cap are determined by the load bearing capacity of the soil.
From the cap comes a column or bent.
Piles can be connected by grade beams

17. Pile & Pile Driving Pile Drivers Drop Hammers
Single/Double-Acting Steam
Hydraulic
Diesel Hammers
Vibratory Pile Drivers

18. Caisson or Cofferdam What’s the difference?
Caisson- Boring or drilling a hole and filling with concrete.
Cofferdam- A temporary boxlike structure used to hold back water or earth while work is being done inside it.

22. EXCAVATION HORIZONTAL & VERTICAL LAYOUT BEGIN EXCAVATION
SWELL AND SOIL TYPES
UNSUITABLE SOIL
STRUCTURAL FILL
SITE DRAINAGE
DEWATERING
COMPACTION
BACKFILL
SAFETY
MECHANICAL & ELECTRICAL

23. Excavation Wall Bracing
No matter what restraining system is used to stabilize the sides of an excavation, the walls will have to be braced against lateral pressures exerted by the surrounding soil and water.
Shoring for trenches (trench boxes)
Lateral forces surrounding the structure
Slope back
Different shoring systems
Tiebacks (rock and earth)

24. Protection of Excavations Lateral Forces Deep Excavations
Slope Back- Usually 2:1, The angle of repose at which a soil material will stand without moving
Interlocking Sheet Piling
Steel Soldier Piles- H beam with lagging
Concrete Slurry walls-Shotcrete (pneumatically projected at high velocity onto a surface)

25. Other piling terminology
Battered pile- A pile driven somewhat at an angle so as to resist horizontal forces.
Kelly bar- The equipment on the pile driver that determines the height of the pile to drive.

27. EXCAVATION

29. Terminology In the industry terms can mean different things.
Toe- (1) Any protection from the base of a construction or object to give it increased bearing and stability. (2)That portion of sheeting below the excavated material. (3) To drive a nail at an oblique angle. (4) The junction between the base metal and the face of a filled weld. (5) The part of the base of a retaining wall that projects beyond the face away from the retained material.

35. Excavation Need for Deep Foundations
Removing ground water or dewatering
Amount of material to be removed
Soil swell percentage
For removal and replace
Tons to cubic yards
Protection of Excavation
Sheet Piling
Soldier Piles
Concrete Slurry Walls
Excavation Wall Bracing
Slope back
Shoring
Tiebacks

36. Foundation Sequencing
Drive Piling- Excavate> >[Slope protection/shoring system]> Layout Piles>Drive Piles>Cut off piles>Fine grade/Compact>Structural Fill> Backfill to follow foundation system
Drilled Piling (concrete)- Excavate> >[Slope protection/shoring system]> Layout Piles>Auger piling>Fabricate Cage>Set reinforcing cage>Pour concrete pile>Fine grade/Compact>Structural Fill> Backfill to follow foundation system
Spread Footings-Excavate>[Slope protection/shoring system]>Layout>Fine grade/Compact>Structural Fill> Backfill to follow foundation system

41. EXCAVATION

43. EXCAVATION
TABLE V:2-1. ALLOWABLE SLOPES.Soil typeHeight/Depth ratioSlope angle Stable RockVertical90°Type A¾:153°Type B1:145°Type C1½:134°Type A (short-term)½:163°(For a maximum excavation depth of 12 ft)