Lecture 11- Deep Foundations

Lecture 11- Deep Foundations - C E M 6 2 C o n s t r u c t...

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Unformatted text preview: C E M 6 2 C o n s t r u c t i o n M e t h o d s CEM 602 Construction Methods Lecture 11 Deep Foundation Methods 1 L e c t u r e 1 1- D e e p F o u n d a t i o n M e t h o d s C E M 6 2 C o n s t r u c t i o n M e t h o d s PILE Construction Equipment 2 L e c t u r e 1 1- D e e p F o u n d a t i o n M e t h o d s C E M 6 2 C o n s t r u c t i o n M e t h o d s Power Augers Power-driven rotary auger drills for installing bored piles in clay soils Machines available include: drilling buckets, spiral augers, and continuous flight augers The range of diameters and depths possible is considerable, from 300 to over 5000 mm and down to 100m. Hydraulic power is generally used Uses a rotary table, a rotating kelly drive on a mast or a top-drive rotary head 3 L e c t u r e 1 1- D e e p F o u n d a t i o n M e t h o d s C E M 6 2 C o n s t r u c t i o n M e t h o d s Power Augers Most units have additional pulldown or crowd capability Soil removed from spiral plate augers by spinning them after withdrawal Soil removed from buckets either by spinning or through a single or double bottom opening EU mandatory safety requirement that spoil from an auger should be removed at the lowest possible level L e c t u r e 1 1- D e e p F o u n d a t i o n M e t h o d s 4 C E M 6 2 C o n s t r u c t i o n M e t h o d s Power Augers L e c t u r e 1 1- D e e p F o u n d a t i o n M e t h o d s 5 C E M 6 2 C o n s t r u c t i o n M e t h o d s Casing Oscillators Drilling through sands, gravels, and loose rock formations, may require continuous support by means of casing A casing oscillator imparts a semi-rotating motion to the casing through clamps Vertical rams attached to the clamps enable the casing to be forced down The semi-rotating motion is continuous, which prevents the casing from becoming' frozen' to the soil 6 L e c t u r e 1 1- D e e p F o u n d a t i o n M e t h o d s C E M 6 2 C o n s t r u c t i o n M e t h o d s Casing Oscillators Special double wall casing is always kept tight against the bottom of the hole. For this purpose the casing is jointed. The typical casings (e.g. the Bauer and Casagrande types) have male/female joints which are locked by inserting and tightening bolts manually or by an automatic adapter lock to resist the high rotating or oscillating forces L e c t u r e 1 1- D e e p F o u n d a t i o n M e t h o d s 7 C E M 6 2 C o n s t r u c t i o n M e t h o d s Casing Oscillators L e c t u r e 1 1- D e e p F o u n d a t i o n M e t h o d s 8 C E M 6 2 C o n s t r u c t i o n M e t h o d s Continuous Flight Augers Drilling output with CFA rigs is greater than achievable for standard bored piles The pile is installed in one continuous pass The mast must have an adequate stroke for the auger under the rotary head A kelly may be inserted through the rotary head to increase depth on some rigs Most CFA rigs have crowd capability to assist in penetrating harder formations, and...
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This note was uploaded on 03/17/2012 for the course CEM 602 taught by Professor Amrkandile during the Spring '10 term at American University in Cairo.

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Lecture 11- Deep Foundations - C E M 6 2 C o n s t r u c t...

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