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AUGER CAST PILES
TECHNOLOGY OVERVIEW |
TABLE OF CONTENTS
INTRODUCTION
ADVANTAGES
TYPICAL PILE LOADS
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INTRODUCTION
Auger Cast Piles are installed by rotating a continuously flighted hollow shaft auger into the soil to a specified depth. High strength cement grout is pumped under pressure through the hollow shaft as the auger is slowly withdrawn. The resulting grout column hardens and forms an auger cast pile. Reinforcing, when required, can be installed while the cement grout is still fluid or (in the case of full length single reinforcing bars) through the hollow shaft of the auger prior to the withdrawal and grouting process.
Auger Cast Piles can be used:
- As friction piles - the superstructure load is transferred to the soil through friction between the pile surface and the soil;
- As an end-bearing pile - the superstructure load is transferred through the pile tip into a hard stratum of soil or rock;
- As an anchor pile - hydrostatic or other uplift forces are resisted though a full length tendon embedded in the grout column;
- As a vertical component of a continuous auger cast curtain wall in temporary or permanent shoring systems and below grade walls; and
- As a temporary or permanent diagonal tie-back in auger cast curtain walls, beam and lagging walls, and sheet pile walls.
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ADVANTAGES
Less noise - Auger cast piles are a drilled and pumped pile, not a driven pile. This eliminates the hammer impact noise created by driving piles.
No objectionable vibration - The elimination of a pile-driving hammer allows the installation of auger cast piles adjacent to existing structures without the danger of settlement or damage to existing footings, walls, other structural components, or nearby equipment.
No casing required - During the installation of an auger cast pile, the earth filled auger maintains the shape of the pile hole during the drilling phase. The pressures produced by the grout pump during the withdrawal and grouting phase exceed the lateral pressures exerted by the soil, and while the gout is still fluid, the lateral pressures per foot of depth of the grout exceed those pressures per foot of depth of the soil.
Can be installed in limited headroom conditions - Auger sections can be manufactured to accommodate installation of auger cast piles inside existing buildings with a minimum clearance of 7 to 10 feet.
Soil at each pile hole can be inspected - The grout that is pumped into the pile displaces the existing soil for the entire length of the pile. This displacing action allows the soil along the length to be available for visual inspection and testing. |
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TYPICAL PILE LOADS
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Diameter (inches) |
Loading Range (tons) |
Compressive strength (psi) |
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12" |
10-50 |
3000-4000 |
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14" |
50-75 |
3000-4000 |
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16" |
75-100 |
3500-4500 |
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18" |
100-150 |
4000-5000 |
(actual results vary depending on soil conditions)
The diameters indicated are the most common used for auger cast piles. However, auger cast piles with diameters of 24, 30 and 36 inches have been successfully utilized with tests being conducted as high as 350 tons. Pile design capacities can be verified with several different testing procedures: ASTM D 1143 tests the compressive capacity of a pile by applying a static axial compressive load; ASTM D 4945 tests the compressive capacity of a pile by applying a dynamic axial high-strain impact load; ASTM D 3689 tests the tensile capacity of a pile by applying a static axial tensile load; ASTM D 3966 tests the lateral capacity of a pile by applying a static load perpendicular to the axis of the pile. ASTM D 5882 tests the integrity of the pile shaft by applying a dynamic axial low-strain impact load.
The above text was provided by:
David Schember of United Foundations, Inc
phone: 330-650-0124 or http://www.unitedfoundationsinc.com |
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