The lowest division of a building or other construction, partly or wholly below the surface of the ground, designed to support and anchor the superstructure and transmit its loads diretly to the earth.
A foundation system placed directly below the lowest part of a substructure and transferring building loads directly to the supporting soil by vertical pressure.
The part of foundation bearing directly upon the supporting soil, set below the frostline and enlarged to distribute its load over a greater area.
The horizontal component of resistance developed by a soil mass against the horizontal movement of a vertical structure through the soil.
Passive Earth Pressure
The horizontal component of pressure that a soil mass exerts on a vertical retaining structure.
Active Earth Pressure
The actual pressure developed between a footing and the supporting soil mass, equal to the qoutient of the magnitude of the forces transmitted and the area of contact.
Soil Pressure or Contact Pressure
Soil Pressure Formula
Building Load (P) / Area of Footing (A)
The maximum unit pressure a foundation is permitted to impose vertically or laterally on a supporting soil mass. Allowable bearing pressures for various soil classifications are conservative values permitted by building codes in the absence of geotechnical investigation and testing of the soil.
Allowable Bearing Pressure or Allowable Bearing Capacity, Allowable Bearing Soil Pressure
The gradual subsiding of a structure as the soil beneath its foundation consolidates under loading.
The gradual reduction in the volume of a soil mass resulting from the application of a sustained load and an increase in compressive stress.
A reduction in volume of a soil mass under the action of a sustained load, due chiefly to a squeezing out of water from the voids within the mass and a transfer of the load from the soil water to the soil solids.
Primary Compression or Primary Consolidation
A reduction in volume of a soil mass under the action of a sustained load, due chiefly to adjustment of the internal structure of the soil mass after most of the load has been transferred from the soil water to the soil solids.
The relative movement of different parts of a structure caused by uneven settlement or failure of its foundation.
Overlapping soil stresses may be caused by closely spaced footings or by adjacent footings located at different levels.
*thats why when isolated footings are closely spaced, it is much better to make the foundation in a matt system.
The maximum depth at which soil is frozen or frost penetrates the ground.
An uplift in soil cause by the freezing of internal moisture.
A softening of soil resulting from the thawing of frozen groundwater.
A wall occuring below the floor nearest grade, designed to support and anchor the superstructure.
A concrete slab placed over a dense or compacted base and supported directly by the ground, usually reinforced with welded wiere fabric or a grid of reinforcing bars to control any cracking caused by drying shrinkage or thermal stresses. Separate or Integral footings are required for heavy or concentrated loads. Over problem soils, the slab must be designed as a mat or raft foundation.
Ground Slab or Slab on Grade
A layer of coarse granular materials placed and compacted on undisturbed soil or prepared fill to prevent the capillary rise of moisture to a concrete ground slab.
Something that underlies or serves as a base or foundation.
Substrate or Substratum
A concrete footing extended laterally to distribute the foundation load over a wide enough area that the allowable bearing capacity of the supporting soil is not exceeded.
The continuous spread footing of a foundation wall.
A single spread footing supporting a freestanding column or pier.
A reinforced concrete footing extended to support a row of columns.
A reinforced concrete beam supporting a superstructure at or near ground level and transferring the load to isolated footings, piers, or piles.
Grade Beam or Ground Beam
A continuous or strip footing that changes levels in stages to accommodate a sloping site or bearing stratum.
A reinforced concrete footing connected by a tie beam to another footing in order to balance an asymmetrically imposed load, as at the perimeter of a building site.
Cantilever Footing or Strap Footing
A reinforced concrete footing for a perimeter column or foundation wall extended to support an interior column load.
To avoid rotation or differential settlement, continous and cantilever footings are proportioned to generated uniform soil pressure.
A thick, slablike footing of reinforced concrete supporting a number of columns or an entire building.
A mat foundation reinforced by a grid of ribs above or below the slab.
A mat providing a footing on yielding soil, usually for an entire building, placed so that the weight of the displaced soil exceeds the weight of the construction.
A foundation used in yeilding soil, having for its footing a raft placed deep enough that the weight of the excavated soil is equal to or greater than the weight of the construction supported.
A framework of crossing beams for spreading heavy loads over a large areas.
Grillage or Grid
A composite structure of reinforced concrete slabs and basement walls serving as a mat foundation.
A foundation system that extends down through unsuitable soil to transfer building loads to a more appropriate bearing stratum well below the superstructure.
A system of piles, pile caps, and tie beams for transferring building loads down to a suitable bearing stratum, used esp. when the soil mass directly below the construction is not suitable for the direct bearing of footings.
A stratum of soil or rock on which a footing bears, or to which a building load is transferred by a pile or caisson.
A pile driven at a specified angle to the vertical in order to provide resistance against lateral forces.
A steel band encircling the head of a timber pile to prevent it from splitting when driven.
Drive Band or Pile Ring
The component of a pile hammer, located just below the ram, that transfers the driving force to the pile head.
A cap for protecting a pile head as well as the pile hammer during a driving operation.
Cushion or Cushion Block, Cushion Head
A machine for driving piles, usually composed of a tall framework supporting machinery for lifting a pile in position before driving, a driving hammer, and vertical rails or leads for guiding the hammer.
A long slender column of wood, steel, or reinforced concrete, driven or hammered vertically into the earth to form part of a foundation system.
A pile depending principally on the bearing resistance of soil or rock beneath its foot for support. The surrounding soil mass provides a degree of lateral stability for the long compression member.
End-bearing pile or Point Bearing Pile
The maximum axial and lateral loads permitted on a pile, as determined by a dynamic pile formula, a static load test, or a geotechnical investigation of the foundation soil.
Allowable pile load
The deviation of a pile from its plan location or from the vertical, resulting in a reduction of its allowable load.
The permitted deviation of a pile from the vertical, for which a reduction in allowable load is not required.
A heavy steel pipe driven with the lower end either open or closed by a heavy steel plate or point and filled with concrete. An open-ended pipe pile requires inspection and excavation before being filled with concrete.
A steel H-section driven as a pile, sometimes encased in concrete to a point below the water table to prevent corrosion. H-sections can be welded together in the driving process to form any length of pile.
A log driven usually as a friction pile, often fitted with a steel shoe and a drive band to prevent it from splitting or shattering.
The hard, pointed or rounded foot of a pile or caisson for piercing underlying soil.
Shoe or Drive Shoe
A precast, often prestressed concrete column, having a round, square, or polygonal section and sometimes an open core, driven into the earth by a pile driver until it meets the required resistance.
Precast Concrete Pile
A pile constructed of two materials, such as a timber pile having a concrete upper section to prevent the portion of the pile above the water table from deteriorating.
A pile depending principally on the frictional resistance of surrounding earth for support.
The friction developed between the sides of a pile and the soil into which the pile is driven, limited by the adhesion of soil to the pile sides, and the shear strength of the surrounding soil mass.
An additional load on a pile resulting from the settling of fill, which tends to drag the pile downward into the soil.
A zone in a loded soil mass bounded by an arbitrarily selected isobar of stress, as from a single or number of friction piles.
A line connecting points of equal pressure.
Any of several formulas by which the allowable axial load on a pile can be calculated from the energy required for a pile hammer to advance the pile foot a specified distance into the subsoi.
Dynamic Pile Formula
A test for determining the allowable axial load on a single pile, usually a fraction of the load required to reach a yield point, a point of resistance, or a point of refusal.
Static Load Test
The point at which a pile load causes specified net settlement after being applied continuously for a specified period of time.
point of resistance
The point at which no additional settlement takes place after a pile has been loaded continuously for a specified period of time.
Point of Refusal
The point at which an increase in pile load produces a disproportionate increase in settlement.
A reinforced concrete slab or mat joining the heads of a cluster of piles to distribute the load from a column or grade beam equally among the piles.
A reinforced concrete beam distributing the horizotal forces from an eccentrically loaded pile cap or spread footing to other pile caps or footings.
A pile constructed by placing concrete into a shaft in the ground.
Cast-in-place concrete pile
A concrete pile constructed by driving a steel pipe or casing into the ground until it meets the required resistance and then filling it with concrete.
A cylindrical steel section, sometimes corrugated or tapered for increase stiffness, driven or dropped in place to serve as a form for a cast-in-place concrete pile.
A heavy steel tube or core that is inserted into a thin-walled casing to prevent it from collapsing in the driving process, and then withdrawn before concrete is placed in the casing.
A concrete pile constructed by driving a concrete plug into the ground along with a steel casing until it meets the required resistance, and then ramming concrete into place as the casing is withdrawn.
A cast-in-place concrete pile having an enlarged foot to increase its bearing area and strengthen the bearing stratum by compression, formed by forcing concrete out at the bottom of the casing into the surrounding soil.
A bulge cast or formed at the bottom of a cast-in-place concrete pile to enlarge its bearing area nd strengthen the bearing stratum by compression.
A cast-in-place concrete foundation formed by boring with a large auger or excavating by hand a shaft in the earth to a suitable bearing stratum and filling the shaft with concrete.
A pier, esp. when the boring is 2ft (610mm) or larger in diameter to permit inspection of the bottom.
The base of a caisson enlarged to increase its bearing area.
A caisson that is drilled into a stratum of solid rock rather than belled.
A socketed caisson having a steel H-section core within a concrete-filled pipe casing.
A base for a footing in soft soil, made by compacting sand in a cavity left by a timber pile.