Bulb Piles –Franki Piles or pressure injected footings –Special form of cast in place pile with an enlarged base for increased load bearing F 10-4 Minipiles, micro piles –Small diameter piles (2-8 inches) –High capacity (to 60 ton) –Used where there is restricted access or headroom to underpin or temp support a building –Usually placed as a steel casing with reinforcing then whole thing is grouted to soil

Pile driving Drop hammer – ancient pile driver F10-5 –Pile driver is usually crane driven –Pile driver consists of a Drop weight Leads – guide for weight Pile driving consists of placing a pile in the lead Dropping the weight Lifting weight Repeat Must have a stop block to keep weight on leads

Power Hammer Pile Drivers –Use a working fluid to drive hammer –Steam or compressed air was first type used –Hydraulic is newer version –Single acting hammer Fluid lifts weight which then falls down –Double acting hammer Fluid lifts weight and drive weight down Hammer Lighter than single acting

Diesel hammer –F10-6 explain steps

Pile Driving Procedures –F10-8 Impact type pile driver –F 10-7 Power hammers work on piles not driven straight down

Piers & Caissons –Pier – reinforced concrete column constructed below ground surface Drilled piers – holes drilled in cohesive soils are filled with a slurry until concrete is poured Holes drilled in non-cohesive soil has a liner which can be pulled as concrete is placed Caisson structure used to provide all around lateral support to an excavation –Pneumatic caisson – air or watertight structures open at bottom to permit excavation Air pressure keeps water & soil out Must take safety into account – bends Brooklyn Bridge