Downloaded 23 times
More Related Content
Foundation
- 1. Introduction Types ofSoils and Characteristics Construction of Foundation Types of Foundations Foundations Rakesh J. Pillai National Institute of Technology Warangal January 29, 2015 Rakesh J. Pillai NITW Foundations
- 2. Introduction Types ofSoils and Characteristics Construction of Foundation Types of Foundations Outline 1 Introduction Foundation Loads on Foundations Settlements of Foundations 2 Types of Soils and Characteristics 3 Construction of Foundation Foundation Construction 4 Types of Foundations Foundation Types Shallow Foundation Deep Foundation Rakesh J. Pillai NITW Foundations
- 3. Introduction Types ofSoils and Characteristics Construction of Foundation Types of Foundations Foundation Outline 1 Introduction Foundation Loads on Foundations Settlements of Foundations 2 Types of Soils and Characteristics 3 Construction of Foundation Foundation Construction 4 Types of Foundations Foundation Types Shallow Foundation Deep Foundation Rakesh J. Pillai NITW Foundations
- 4. Introduction Types ofSoils and Characteristics Construction of Foundation Types of Foundations Foundation Introduction Foundation Function of a foundation is to transfer the structural loads from a building safely into the ground Foundations should rest on soil with sufficient strength and competent to carry the massive loads coming from buildings A variety of soils, rocks and water conditions may be encountered below the ground surface; hence foundation design is a highly specialized field of civil engineering Rakesh J. Pillai NITW Foundations
- 5. Introduction Types ofSoils and Characteristics Construction of Foundation Types of Foundations Loads on Foundations Outline 1 Introduction Foundation Loads on Foundations Settlements of Foundations 2 Types of Soils and Characteristics 3 Construction of Foundation Foundation Construction 4 Types of Foundations Foundation Types Shallow Foundation Deep Foundation Rakesh J. Pillai NITW Foundations
- 6. Introduction Types ofSoils and Characteristics Construction of Foundation Types of Foundations Loads on Foundations Loads on Foundations Dead load Live load Wind load Earthquake load Uplift pressures (eg. foundations on expansive soils and marine foundations) Rakesh J. Pillai NITW Foundations
- 7. Introduction Types ofSoils and Characteristics Construction of Foundation Types of Foundations Settlements of Foundations Outline 1 Introduction Foundation Loads on Foundations Settlements of Foundations 2 Types of Soils and Characteristics 3 Construction of Foundation Foundation Construction 4 Types of Foundations Foundation Types Shallow Foundation Deep Foundation Rakesh J. Pillai NITW Foundations
- 8. Introduction Types ofSoils and Characteristics Construction of Foundation Types of Foundations Settlements of Foundations Settlements of Foundations Deformations of the foundation soil is called settlement Should be with in permissible limits Two types of settlements: Uniform settlement - All parts of the building settles uniformly Differential settlement - Some portion settles more than other portion Figure : (a) No settlement, (b) Uniform settlement, (c) DifferentialRakesh J. Pillai NITW Foundations
- 9. Introduction Types ofSoils and Characteristics Construction of Foundation Types of Foundations Types of Soils and characteristics Loads from buildings are transfered through foundation to the soil underground Soils usually classified based on the particle size Boulders and cobbles (large size particles) Gravel - coarse grained particles with size > 5 mm Sand - particle size varies from 5mm - 0.075mm (load transfer by friction) Silt - particle size varies from 0.075mm - 0.002mm (intermediate behaviour of sand and clays) Clay - particle size < 0.002 mm (load transfer by cohesion) Peat - organic, not suitable for foundations Rakesh J. Pillai NITW Foundations
- 10. Introduction Types ofSoils and Characteristics Construction of Foundation Types of Foundations Sand and Clays Sand Sand is cohensionless and the resistance is offered by the internal friction between the particles Clay In the case of clay, cohesion between the particles offers the resistance Rakesh J. Pillai NITW Foundations
- 11. Introduction Types ofSoils and Characteristics Construction of Foundation Types of Foundations Foundation Construction Outline 1 Introduction Foundation Loads on Foundations Settlements of Foundations 2 Types of Soils and Characteristics 3 Construction of Foundation Foundation Construction 4 Types of Foundations Foundation Types Shallow Foundation Deep Foundation Rakesh J. Pillai NITW Foundations
- 12. Introduction Types ofSoils and Characteristics Construction of Foundation Types of Foundations Foundation Construction Construction of Foundation 3 important steps before construction of foundations Excavation: It is an important step in construction of foundation; should be excavated to a level where sufficient bearing capacity of soil is available. A variety of machines are used for excavation (Dozers, Backhoes) The sides of excavation to be protected from caving Benching Sheeting (solder beams, slurry walls, sheet piles etc.) Bracing (cross-slot, rakers, tie backs etc.) De-watering using well-points and sumps Each of these steps explained in following slides Rakesh J. Pillai NITW Foundations
- 13. Introduction Types ofSoils and Characteristics Construction of Foundation Types of Foundations Foundation Construction Construction of Foundation Excavation Machines for excavation - dozers, backhoe Machines for taking out soil - bucket loaders, scrapers For hard strata - Power shovels, tractor mounted rippers, pneumatic hammers For harder strata - drop balls, hydraulic splitters, blasting (a) Dozer and (b) Backhoe Rakesh J. Pillai NITW Foundations
- 14. Introduction Types ofSoils and Characteristics Construction of Foundation Types of Foundations Foundation Construction Construction of Foundation Protection from Caving Benched Excavation Used when there is no restriction or when plenty of space is available Slopes provided less than angle of repose and benches are provided in between, for greater depths Less expensive and commonly used Rakesh J. Pillai NITW Foundations
- 15. Introduction Types ofSoils and Characteristics Construction of Foundation Types of Foundations Foundation Construction Construction of Foundation Protection from Caving Sheeting - Solder beams and lagging Rakesh J. Pillai NITW Foundations
- 16. Introduction Types ofSoils and Characteristics Construction of Foundation Types of Foundations Foundation Construction Construction of Foundation Protection from Caving Sheeting - Sheet piles (long structural section with vertical inter-locking system that creates a continuous wall) Made of different materials (steel is commonly used) Available in different cross sections (shape) Rakesh J. Pillai NITW Foundations
- 17. Introduction Types ofSoils and Characteristics Construction of Foundation Types of Foundations Foundation Construction Construction of Foundation Protection from Caving Bracing - Different types Crosslot bracing Rakers Tiebacks Rakesh J. Pillai NITW Foundations
- 18. Introduction Types ofSoils and Characteristics Construction of Foundation Types of Foundations Foundation Construction Construction of Foundation Protection from Caving Tieback Installation A Rotary drill hole B Insert and grount tendons C Tendons stressed and anchored Rakesh J. Pillai NITW Foundations
- 19. Introduction Types ofSoils and Characteristics Construction of Foundation Types of Foundations Foundation Construction Construction of Foundation Dewatering Process of removing water and/or lowering the water table within the construction site Purpose of dewatering is to provide a dry working platform If water table is above the working platform there are three options: Keep water out Let water in and then remove it using a pump system Combination of the above two Rakesh J. Pillai NITW Foundations
- 20. Introduction Types ofSoils and Characteristics Construction of Foundation Types of Foundations Foundation Construction Construction of Foundation Dewatering Watertight Barrier Walls Barrier must reach an impervious strata to keep the water out Different types Slurry walls Sheeting (sheet piles are widely used) Barrier should resist the hydrostatic pressure Rakesh J. Pillai NITW Foundations
- 21. Introduction Types ofSoils and Characteristics Construction of Foundation Types of Foundations Foundation Types Outline 1 Introduction Foundation Loads on Foundations Settlements of Foundations 2 Types of Soils and Characteristics 3 Construction of Foundation Foundation Construction 4 Types of Foundations Foundation Types Shallow Foundation Deep Foundation Rakesh J. Pillai NITW Foundations
- 22. Introduction Types ofSoils and Characteristics Construction of Foundation Types of Foundations Foundation Types Type of Foundations Two types Shallow foundations Deep foundations Based on whether the load transfer is at deeper depths or shallower depths The depth of load transfer depends on: Soil strength Ground water conditions Foundation loads Construction methods Impact on adjacent property Rakesh J. Pillai NITW Foundations
- 23. Introduction Types ofSoils and Characteristics Construction of Foundation Types of Foundations Shallow Foundation Outline 1 Introduction Foundation Loads on Foundations Settlements of Foundations 2 Types of Soils and Characteristics 3 Construction of Foundation Foundation Construction 4 Types of Foundations Foundation Types Shallow Foundation Deep Foundation Rakesh J. Pillai NITW Foundations
- 24. Introduction Types ofSoils and Characteristics Construction of Foundation Types of Foundations Shallow Foundation Shallow Foundations Requirements Suitable soil bearing capacity Undisturbed soil or engineered fill Basic types or configurations Column footings or isolated footings (spread footings and stepped footings) Wall or strip footings Other types Column footings with tie beams Combined footing Raft (or Mat) footing Rakesh J. Pillai NITW Foundations
- 25. Introduction Types ofSoils and Characteristics Construction of Foundation Types of Foundations Shallow Foundation Shallow Foundations Strip footing is continuous and takes load directly from the load bearing walls Column footings or isolated footings support and take load from a single column sometimes the c/s area is increased with depth to form a spread footing sometimes the c/s area is increased in steps to form stepped footing Combined strip and isolated footing Rakesh J. Pillai NITW Foundations
- 26. Introduction Types ofSoils and Characteristics Construction of Foundation Types of Foundations Shallow Foundation Shallow Foundations Combined footing is when two columns are provided on the same footing (usually provided when the spacing between the columns are less) In the case of raft or mat foundation, a single foundation (in the form of mat) is provided for all the columns of the building Mat foundation Rakesh J. Pillai NITW Foundations
- 27. Introduction Types ofSoils and Characteristics Construction of Foundation Types of Foundations Deep Foundation Outline 1 Introduction Foundation Loads on Foundations Settlements of Foundations 2 Types of Soils and Characteristics 3 Construction of Foundation Foundation Construction 4 Types of Foundations Foundation Types Shallow Foundation Deep Foundation Rakesh J. Pillai NITW Foundations
- 28. Introduction Types ofSoils and Characteristics Construction of Foundation Types of Foundations Deep Foundation Deep Foundation Deep foundations transfer the building load deep in to the earth Piles, Cassions, Well foundations Rakesh J. Pillai NITW Foundations
- 29. Introduction Types ofSoils and Characteristics Construction of Foundation Types of Foundations Deep Foundation Deep Foundation Different Types of Piles Based on Load Transfer Friction piles - load transferred by the frictional resistance between the pile and the soil End bearing piles - load transferred to a hard strata through the end of pile (point loading) Based on construction method (for concrete piles) Precast Driven piles - piles are casted in a yard, brought to the site and driven in to the soil (by hammer blows or other methods) Bored cast-in situ piles - a bore (hole) of required diameter and depth is dug and the reinforcement and concrete is placed to form the pile Driven cast-insitu piles - a casing is driven initially and the reinforcement and concrete is placed after taking out soil inside the casing Rakesh J. Pillai NITW Foundations
- 30. Introduction Types ofSoils and Characteristics Construction of Foundation Types of Foundations Deep Foundation Deep Foundation Pile material Steel (H - piles or steel pipe piles) Concrete (cast-in situ or precast) Timber Composite Rakesh J. Pillai NITW Foundations
- 31. Introduction Types ofSoils and Characteristics Construction of Foundation Types of Foundations Deep Foundation Deep Foundation Precast steel (H piles) and concrete piles Rakesh J. Pillai NITW Foundations
- 32. Introduction Types ofSoils and Characteristics Construction of Foundation Types of Foundations Deep Foundation Thank You !!! Rakesh J. Pillai NITW Foundations