Mapa mental
Piled Foundations
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Piled Foundations
Types of Piles
- End bearing
- terminate in hard material
- strength = resitance of stratum at the toe
- Friction
- carrying capacity by skin friction or adhesion
- occurs when cannot reach impenetrable stratum
- carrying capacity from end bearing and skin friction
- Negative Skin
- affects poorly compacted fill
- produces a downward drag along the pile shaft
- additional load on pile
- occurs as the fill consolidates under its own weight
- Piled raft / settlement reducing
- beneath the central part of a raft foundation
- reduce differential settlement
- reinforce the soil beneath the raft
- prevent dishing of the raft in the centre
- End bearing
Construction Methods
- DISPLACEMENT
- soil is diplaced radially and vertically
- driven or jacked
- impact
- dropping a weight
- most common method of insertion
- weight half that of the pile
- raised in a guide and released to strike the pile head
- diesel hammer
- rapid controlled explosions
- explosions raise ram which drives pile
- ram smaller than the weight used
- frequency of blows
- most suitable for non-cohesive granular soils
- driving - vibratory method
- non-cohesive granular soils esp sand
- vibration excites the soil grains making the soil free flowing
- reduces friction along pile shaft
- produced electrically or hydraulically
- large energy
- damage equipment
- noise
- vibration = settlement f nearby buildings
- dropping a weight
- hydraulic jacking
- pre-determined depth (geotech eng) or to 'refusal'
- jacking methods
- most common = underpinning existing structures
- short pile can be inserted
- uses underside of structure as reaction
- impact
- precast concrete or steel
- full length reinforced (prestressed)
- jointed (reinforced)
- hollow (tubular) section
- Helical (screw) cast in place
- auger
- soil is compacted, not removed
- auger is carried on a hollow stem
- filled with concrete
- slowly unscrewed leaving pile
- REPLACEMENT
- soil is removed
- hole filled
- concrete
- pre-cast concrete
- dropped and grouted
- small diameter bored CIP (mini piles)
- Large diameter bored CIP
- spiral short flight auger
- drilling bucket
- rotated
- depth up to 70m
- Partially preformed
- annular sctions lowered into BH
- = hollow column
- suitable where ground is waterlogged
- reinforcement placed and grout forced down to the base
- displaces water
- annular sctions lowered into BH
- Grout or concrete intruded
- enviro advantages
- noise & vibration low
- no temp BH wall casing
- no bentonite slurry = suitable for clay and granular
- screwed by continuous flight auger
- grout forced down hollow shaft
- can be reinforced
- enviro advantages
- suitable for clays
- BH walls only require support at GL
- irregular interface btwn PS and Soil
- good skin friction under loading
- DISPLACEMENT
Factors influencing choice
- location
- over water
- driven piles
- moderate loading
- driven CIP
- heavy structures
- large diameter BP
- underpinning
- jacked piles
- over water
- ground conditions
- boulders or clays
- economically not driven piles
- ground heave
- economically not driven piles
- loose water bearing sand
- not bored piles
- cohesion less soil
- not jacked piles
- excavations collapse
- not jacked piles
- boulders or clays
- durability
- concrete - no corrosion
- sulphates or acids in soil
- cost & time
- materials
- time required
- test loading
- cost of engineer
- cost of organisation and overheads
- location
Definition
- slender column
- variety of materials
- transmit foundation loads
- reach stronger ground
Imágenes y archivos del mapa
Información
- Descripción
- Types Construction Methods Factors Pile Groups Examples
- Creado por
- Rachael Goodson
- Visitas
- 15
- Valoración