Foundation Engineering ECIV 4352

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Cecil Thomas
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1 Foundation Engineering ECIV 4352 Instructor : Dr. Jehad Hamad Chapter (11) Deep Foundation

2 Chapter 11 Pile Foundation

3 Foundation- Design Considerations Factors to be taken into consideration when determining the type of the building foundations: Function of the structure Loads from the structure Bearing capacity of foundation material Total and differential settlement of foundation Uplift forces acting on the foundation Costs October 16, 2016 ECIV 2204 Engineering Geology Civil Engr. Dept. 3

4 When is it needed Top layers of soil are highly compressible for it to support structural loads through shallow foundations. Rock level is shallow enough for end bearing pile foundations provide a more economical design. Lateral forces are relatively prominent. In presence of expansive and collapsible soils at the site. Offshore structures Strong uplift forces on shallow foundations due to shallow water table can be partly transmitted to Piles. For structures near flowing water (Bridge abutments, etc.) to avoid October the 16, 2016 problems ECIV 2204 due Engineering to erosion. Geology 4 Civil Engr. Dept.

5 Types of Piles Steel Piles Pipe piles Rolled steel H-section piles Concrete Piles Pre-cast Piles Cast-in-situ Piles Bored-in-situ piles Timber Piles Composite October 16, 2016 Piles ECIV 2204 Engineering Geology Civil Engr. Dept. 5

Steel Piles: Facts Usual length: 15 m 60 m Usual Load: 300 kn 1200 kn Advantage: Relatively less hassle during installation and easy to achieve cutoff level.

6 Steel Piles: Facts Usual length: 15 m 60 m Usual Load: 300 kn 1200 kn Advantage: Relatively less hassle during installation and easy to achieve cutoff level. High driving force may be used for fast installation Good to penetrate hard strata Load carrying capacity is high Disadvantage: Relatively expensive Noise pollution during installation Corrosion October 16, 2016 ECIV 2204 Engineering Geology Civil Engr. Dept. 6

7 Difficult October to transport 16, 2016 Concrete Piles: Facts Pre-cast Piles: Usual length: 10 m 45 m Usual Load: 7500 kn 8500 kn Cast-in-situ Piles: Usual length: 5 m 15 m Usual Load: 200 kn 500 kn Advantage: Relatively cheap It can be easily combined with concrete superstructure Corrosion resistant It can bear hard driving Disadvantage: ECIV 2204 Engineering Geology Civil Engr. Dept. 7

Types of Piles Based on Their Function and Effect 0f Installation Piles based on their function End Bearing Piles Friction Piles Compaction Piles

8 Types of Piles Based on Their Function and Effect 0f Installation Piles based on their function End Bearing Piles Friction Piles Compaction Piles Anchor Piles Uplift Piles Effect of Installation Displacement Piles Non-displacement October 16, 2016 ECIV Piles 2204 Engineering Geology Civil Engr. Dept. 8

10 Soil Bearing Capacity The soil bearing capacity needs to be determined. This can be done by: Local or State Building Codes Uniform Building Code (UBC) Soil testing/analysis Site inspection and simple soil testing Soil borings taken at proposed foundation locations

Foundations - Deep Pile Foundations - vertical structural members that are forced into the ground by pile drivers (similar to driving nails into wood) Caissons similar to pile foundations, but are

11 Foundations - Deep Pile Foundations - vertical structural members that are forced into the ground by pile drivers (similar to driving nails into wood) Caissons similar to pile foundations, but are created by auguring (drilling ) a deep hole into the ground and then filling the hole with concrete. Caissons may be belled at the base. Steel reinforcement may also be used. Caissons can extend to bedrock.

12 Foundations Mat or raft foundations the entire building is placed on one large continuous footing. Typically used in locations where the soil is weak/poor and bedrock is too deep. Mat foundations with caissons or piles a combination of a mat foundation with piles or caissons.

13 Introduction Pile foundation used to support structure poor quality soil bearing capacity failure excessive settlement End-bearing pile Pile driven until it comes to rest on a hard impenetrable layer of soil or rock Friction pile load of the structure must come from the skin friction or adhesion between surface of the pile and the soil

Caissons: are a form of deep foundation which are constructed above ground level, then

14 Piers : are foundations for carrying a heavy structural load which is constructed in-situ in a deep excavation. Caissons: are a form of deep foundation which are constructed above ground level, then sunk to the required level by excavating or dredging material from within the caisson. October 16, 2016 ECIV 4352 Foundation Engineering Civil Engr. Dept. 14

15 Drilled Caissons Deep foundation that is constructed in-place Drilling and casting concrete in-place straight-shaft belled ( reduced contact pressure) Advantages lighter and less expensive drilling equipment quieter than pile drivers reduce ground vibrations visual inspection of subsoil

20 Advantages and Disadvantages of Drilled Pier Foundation Advantages 1- Pier of any length and size can be constructed at the site, 2- Construction Equipment is normally mobile and construction can be proceed rapidly

31 Bearing Capacity of Caissons Q(ult) = Q(friction) + Q(tip) Cohesive soils Q(total) = cnc *A(bottom) + f*a(shaft) Cohesionless soils Q(ult) = p(v)*nq*a(bottom) + (Ko*p(v)*tan )A(shaft)

Assalamualaikum & Good Morning (May All Of You Gain A Better Understanding)

Assalamualaikum & Good Morning (May All Of You Gain A Better Understanding) Always Try To Do The Best In Your Life TYPES OF FOUNDATION TYPES OF FOUNDATION a) Shallow Foundation System i) Spread Foundation