U Lead

See Box Lead.

Ultimate Bearing Value of Pile

1. The maximum load which a single pile will support.
2. A load such that any increase will cause objectionable progressive settlement of the pile.

Ultimate Bearing Value of Pile Foundation

The maximum load, computed as a total load or as a load per pile, which the foundation will support without objectionable progressive movement. See Safe Load.

Ultrasonic Testing

Method of testing structural integrity of a pile. High frequency waves are transmitted to the pile and time required for a reflected wave to return to the top of the pile is measured.

Uncased Concrete Pile

A column of concrete placed and left in the ground without encasement. See Augered Pile.

Uncased Pile

Pile formed by drilling a hole into the ground and filling the hole with concrete without using a liner or tube. May be reinforced.

Underhung Leads

Pile hammer leads that hang from the crane boom by way of straps or cables.

Underpinning

Piles, piers, walls, sheet piling, or other supports added to or replacing foundations under an existing structure to preserve the integrity of the structure or increase its load capacity.

Under-Ream

Enlargement of the lower end of an augered or drilled pile, shaft or caisson to increase its bearing area. Also called Bell.

Underwater Driving

Driving a pile underwater by operating the hammer under water. Provision must be made for exhaust to the atmosphere for air or steam powered hammers.

Unit Weight

The weight per unit volume of a material such as soil, water, concrete, etc. Typically expressed as pounds per cubic foot, grams per cubic centimeter, or kilograms per cubic meter.

Uplift Capacity

The resistance of piles to pulling out of the ground. The ability of a pile to resist uplift and overturn forces due to wind and hydrostatic pressure. See Anchor Pile.

Valve

A part in the hammer which directs the inlet and exhaust fluid to the proper section of the hammer at the proper point in the stroke.

Valve Chest

The part mounted on the face of double-acting fluid-valve hammers in which the spool valve operates.

Valve Cover

A part in double-acting mechanical-valve hammers which fits over the valve and holds oil to lubricate the valve. The same as the "oil reservoir" in single-acting hammers.

Vane Shear Test

A four-bladed vane is forced into undisturbed soil ahead of a sampling tube and rotated so the soil shears. Peak and remolded shearing resistance is recorded.

Vertical Earth Boring Machine

See Continuous Flight, Auger.

Vertical Travel Leads

See Leads, Semifixed.

Vibrator

Power tool used to agitate and consolidate freshly placed concrete and produce close contact with the form.

Vibratory Driver/Extractors

A pile driving and extracting machine which is mechanically connected to a pile and drives or extracts the pile by oscillating it through the soil. Power source may be either electric or hydraulic.

Vibroflot

The instrument used, with an internal motor driving eccentric weights.

Vibroflotation

Trade name for means of densifying non-cohesive soils by deep vibration coupled with air or waterjetting.

Void Ratio

The total colume occupied by a soil mass includes the soil particles plus void spaces (which in nature always exist between the particles because of their irregular shape). The void ratio is the ratio of the void space volume to the volume of soil solids.

Vulcan

A pile driving hammer, the term is most often applied to any single-acting hammer, but is actually a manufacturer's name.

Waffle Plate

Used between two wood memberst to prevent slippage after bolt up.

Wakefield Pile

Timber sheet piles consisting of three planks bolted or spiked together, with the middle plank offset so as to form a tongue along one edge and a corresponding groove on the other. See Sheet Pile.

Waking Up a Pile

1) The time it takes to get a pile in motion after it has set up in the soil. For example, a 120-foot long H-Pile may be driven in two steps. The first 50 feet are driven and then the second 50 foot section is welded or spliced to the first section already driven. Due to delays in welding time, it could be days or even weeks before the second section is driven. This time delay allows the pile to set up in the soil. When driving begins for the installation of the second section, the driving may start out difficult due to the soil set up on the first section. In many cases, the pile begins moving again once the hammer has hit the pile a few times. This is called “waking up the pile”.

2) When extracting piles using a vibratory pile driver/extractor, it is common practice to attempt to drive the pile to break the friction between pile and soil. This once this friction is broken the crane operator can pull on the pile and remove it with less difficulty. The act of trying to drive the pile for a short time prior to extracting it is called “waking up the pile”.

3) Prior to the introduction of the vibratory pile driver/extractor, when extracting piles using a pile line and a dead pull, it was common to strike the pile with an impact hammer to break the friction. This would be called “waking up the pile”.

4) Any method used to break the friction of the soil from the pile prior to driving or extracting.

Wale (Waler)

1. A horizontal structural member placed laong a line of piles to accept the load from the piles and trasmit it to struts, shoring or other bracing.
2. A rubbing strip or fender on the face of docks.

Wall Thickness

The thickness of the metal of a pile.

Wash Boring

1. A method of advancing a boring by means of rotary drilling utilizing water or a bentonite slurry to stabilize the sides of the opening.
2. A method of examining soil, usually in soft soil or clay, by driving a pipe into the ground and then inserting a small pipe inside of it, through which water is forced to wash out soil particles in water suspension for examination. Also called Water Jet. See Airlift.

Water Content

The ratio of the quantity (by weight) of water in a given volume of soil mass to the weight of the soil solids, typically expressed as a percentage.

Water Jet

See Jetting.

Water Stop

A rubber, neoprene or some composition material used to prevent passage of water through a joint.

Water Table

The subsurface elevation at whcih water will usually be present. Also called Groundwater.

Wave Equation

A mathematical equation that describes the mechanics of force transmission along an elastic rod (pile_ that has been subjected to a mass having a specific initial velocity from which the energy transmission and stress at any point along a pile being driven can be computed. First applied to pile installation by E. A. L. Smith.

Wave Speed (C)

The speed of a stress wave in various materials. It is described by the formula:

C= E/P1/2

E = Velocity in feet/sec.
P = Mass density>br>H = Height of fall in feet

e = Hammer efficiency

For a double-acting steam/air hammer, the impact velocity is:

V = (2GEe/W)1/2

E = Rated energy
W = Weight of the ram
e = Hammer efficiency

Ways

See Side Channels.

WEAP

Title of computer program standing for Wave Equation Analysis of Piles.

Wedge

A tapered piece of wood or metal.

Weephole

A small hole, as in a retaining wall, to drain water to the outside.

Well Point

The perforated end section of a well pipe which permits the groundwater to be drawn into the pipe for collection and dispoasl or use.

Whaler

A horizontal bracing member used in form construction to support the stud uprights on concrete forms.

Wharf

The generic term for a landing place or platform built at the edge or out into water for the berthing of vessels.

Wheel

Term for the circular hub used to steer a vehicle, boat, or etc...

Wheel House

The house or cabin where the wheel is contained for steering the boat.

Whip Check

A cable or chain attached to each side of a joint in a pressure hose to keep it from flying around or whipping if the joint were to become uncoupled. A safety device required on all air hoses.

Whipping

The tight wrapping of the ends of the rope with a small twine to prevent it from unlaying and fraying.

Whiskey Pile

Term used when you are on the job working, you can buy whiskey because you are there and getting paid. In the past, pilebucks worked hard and drank hard.

Whistle Bit

A term for working past the start of lunch break or working past shift end. It happens when one does not keep track of time, or give themselves enough time to pick up tool before days end.

Wide Flange

Rolled structural steel section in an H shape but greater depth than flange width and flanges thicker than the web. See Steel H-Pile.

Wild Hammer

A hammer with prongs, pants or skirts, attached is set on the pile and the pile is driven without the use of leads.

Windlass

A simple winch that uses a crank or lever to turn the drum.

Wing Nut

An internally threaded fastener with two projecting ears to facilitate turning and tightening by hand.

Wing Wall

Short section of wall along the edge of an abutment. Used to retain soil, stabilize the abutment, and divert water into an opening, such as a culvert.

Wings

Short length or strips of steel welded near the toe of a steel H-pile to increase its bearing capacity.

Working Load

See Design Load.

Yoke

A collar or clamp installed around a column form to prevent spreading during placement of concrete. Mechanical assembly for a slipform, which prevents the forms from spreading and trasfers the load of the forms to jacks.

Young's Modulus (E)

See Modulus of Elasticity.