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Glossary of Piledriving and Foundation Construction Terms

Welcome to the APE Gloassary for piledriving and foundation construction terms. This is a great place to look for terms that you may be unfamiliar with when working with or researching piledriving technologies. This glossary also contains terms unrelated to piledriving, but that are frequently used on and around foundation construction projects. If you have a question or have term that you would like to add and do not know who to call please contact the APE Headquarters in Washington at (800) 248-8498. Business hours are from 8:00 AM to 5:00 PM Pacific Time. For less immediate inquiries, or if you would like an APE sales representitive to get in contact with you, please visit the APE Contact Request Form.

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Letter G

G-Mandrel A two segment mandrel actuated by a hydraulic cylinder pulling on cables which pass over sheaves in a manner to force the two segments apart to hold a corrugated shell for driving.
G. C. General Contractor
Gang Form: A large form panel made up of smaller panel sections. (aka Flying Forms)
Gate See Pile Gate.
Geotechnical Engineer An engineer with specialized training and knowledge of soils and rocks, employed to do soil investigations, design of structure, foundations and provide field observations.
Gibs 1. The guides that attach a diesel hammer and its tripping device to a spud lead.
2. See Side Channels.
Gins or Gin Pole Sometimes applied to a separate mast or boom used to hoist piles or other heavy objects. See Leads.
Girts A stiffening member passing around the outside of a structure, or part of a structure, for the purpose of strengthening or protecting it.
Glacial Till Material deposited by glaciation, usually a wide range of particle sizes, not subjected to the sorting action of flowing water.
Glommer A clamping device used in rigging for picking up steel plate. (see Plate Clamp)
Glut A short piece of timber placed between bracing and a pile as a filler.
Go-For The low man on the construction crew who goes for ...
Gow Caisson A short cylinder of steel plate large enough for a man to work inside; as excavation proceeds, smaller cylinders are set inside until bearing stratum is reached. The telescoped cylinders are withdrawn as concrete is placed.
gpd/gpm Gallons per day (minute). A unit of measurement of the flow of liquids.
Grade 1. The elevation of the natural ground level of any point on a project site.
2. The cut-off elevation of the pile.
Grade Line The level of the ground at the building line.
Grade Point The level of finished concrete in a form.
Grade Stake A stake driven into the ground that locates the finished level of the ground at that point.
Gravel Small stones or fragments of stone generally smaller than 3 in. and large than 1/4 in. in size.
Gravity Hammer A weight configured to slide in pile hammer leads or within a hollow pile which has formed bale or swivel at its top by which it can be mechanically lifted and dropped to drive pile. Also called Drop Hammer.
Greenheart A very hard, naturally durable wood sometimes used for piling; native to the Amazon area. Less durable than pressure treated wood especially in resistance to marine borers.
Grid A template for spotting piles in prescribed locations. See Pile Template.
Grillage A framework of structural horizontal members crossed in layers and placed on the tops of piles or pile caps to support a structural load.
Grip Plate A steel galvanized square plate with a see through pattern and points on both sides, used for bolting up pilings and timbers. (see Waffle Plate)
Grit Angular, rough, hard particles of sand, gravel or crushed stone in a loose form.
Groin 1. A structure built out from, perpendicular to or making an angle with the shoreline. Generally built of pressure treated close timber piling, sheet piling driven between guide wales and piles, or horizontal courses of plank held between vertical timbers or piles driven into the beach so that the structure against which rock is piled is perpendicular to the direction of current or littoral drift. Intended to cut off and prevent the carrying of beach material along the foreshore.
2. A structure, as described above, built out into deeper water and tapering down in elevation so that wave action will not seriously disturb the bottom condistions by scour or undermining to cause destruction of the outshore end. Same as: Spur Dike. Also see Jetty.
Ground Modification A proprietary term for dropping a heavy weight from considerable height to dynamically compact loose soil.
Ground Release Shackle A special shackle that is attached to a hole that has been cut into the upper end of the pile. The ground release shackle can be released from the pile by pulling on a special rope attached to the Ground Release Shackle. The pile crew can release the shackle from the pile by pulling on a rope that causes the pin in the shackle to retract. Ground Release Shackles are used as a safety device to prevent the need for the pile crew to be hoisted into the air to remove the standard type screw/pin shackle. Ground Release Shackles are used on Pile Safety Lines as well as in areas where it is too dangerous to send a pile crewman. Ground release shackles are also used underwater to avoid the need for a diver to go into the water to remove the Pile Safety Line. See Pile Safety Line.
Groundwater See Water Table.
Grout A micture of cement and water or chemicals: for filling voids it is made very thin for pumping under pressure. Rock flour, clay or sand may be added to cement grout for economy. Cement Grout is used in bottom of piles and as an adhesive when adding to hardened concrete. See Chemical Grout.
Grouting, Foundation Grout is pressure injected into deposits of rock containing fissures, cavities, seams, etc.; to solidify and strengthen the formation; to reduce or eliminate a flow of water through the formation; to reduce the hydrostatic uplift under a structure such as a dam. Same as: Pressure Grouting.
Guard Pile Loosely driven, usually treated, timber piles as at a ferry slip. See Fender Pile.
Guide Pile A pile used as a guide for driving other piles or serving as a support for wales for sheet piling.
Guides That part of the pile hammer leads forming a pathway for the hammer, and consisting of parallel members, which mate with side channels of a pile hammer. ALso called Lead Rails, Hammer Guides.
Gumbo A dark-colored, very sticky, highly plastic clay, occuring abundantly in the central and southern parts of the U.S.A.
Gusset A piece of metal or plywood used to strengthen or reinforce intersections of two or more members.
Gut Rod Cold rolled steel used in form work to hold the spread or distance in the form during pouring of concrete. Catheads are placed on the rod and the bolt tightened to hold the form. (aka Pencil Rod)

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