Terms I Flashcards
The earth pressure exerted on the wall which causes the
wall to move away from the soil. The earth surface will tend
to be lowered, and lateral pressure on the wall will be
decreased. If the wall moves far enough away, shear failure
of the soil will occur, and a sliding soil wedge will tend to
move forward and downward.
Active earth pressure
The ratio of the plasticity index to the percentage of clay-
size fraction by weight.
Activity
The Swedish soil scientist who developed a series of tests to
evaluate the relationship between moisture content and soil
consistency.
Albert Atterberg
Refers to the loading per unit area that the soil is able to
support without unsafe movement.
Allowable bearing capacity
It is the working pressure that would ensure a margin of
safety against collapse of the structure from shear failure.
Allowable bearing capacity bearing capacity or Safe bearing
capacity
Developed a new engineering soil classification system
known as Unified Soil Classification System (USCS).
Arthur Casagrande
This defined the boundaries of four states in terms of limits
as follows, liquid limit, the boundary between the liquid and
plastic states, plastic limit, the boundary between the plastic
and semi-solid state and ® shrinkage limit, the boundary
between the semi-solid and solid states.
Atterberg Limits
Refers to the ability of a soil to supports hold up a
foundation and structure.
Bearing capacity
This is the capacity factor in Terzaghi’s bearing capacity
formula which cites the influence of the soil’s cohesion on
its bearing capacity
Bearing capacity factor Nc
This is the capacity factor in Terzaghi’s bearing capacity
formula which cites the influence of surcharge on its bearing
capacity
Bearing capacity factor Nq
This is the capacity factor in Terzaghi’s bearing capacity
formula which cites the influence of soil weight and
foundation width or radius.
Bearing capacity factor Ny
The rise of water in a small diameter tube inserted into the
water the rise being caused by both cohesion of the water
molecules (surface tension) and adhesion of the water to
the tubes wall.
Capillary
He developed an apparatus for the liquid limit test that
consists of a semi spherical brass cup that is repeatedly
dropped onto a hard rubber base from a height of 10 mm by
a cam-operated mechanism.
Casagrande
French scientist who used the principles of calculus for
maxima-minima to determine the true position of the sliding
surface in soil behind a retaining wall.
Charles Coulomb
It is the tests necessary to determine index properties”
Classification test
A type of soil where the fine fractions of the soil have a
plasticity index of 11 or more.
Clayey
It consists of gravel and sand where the individual particles
are large enough to be distinguished without magnification.
Coarse Grained Soil
The ratio of the horizontal to vertical effective stresses.
Coefficient of lateral earth pressure
Another term for coefficient of gradation
Coefficient of curvature or Coefficient of concavity
The ratio of lateral stress to the vertical stress.
Coefficient of earth pressure
The ratio of the square of the diameter corresponding to
30% finer to the product of the effective size and diameter
corresponding to 60% finer.
Coefficient of gradation
Is a proportionality constant determine the flow velocity of
water through soils.
Coefficient of permeability
The ratio of the effective active pressure on the vertical
plane to the vertical effective overburden pressure.
Coefficient of Rankine’s active pressure
The ratio of the effective passive pressure on the vertical
plane to the vertical effective overburden pressure.
Coefficient of Rankines passive pressure
Shear strength of a soil when tested with no lateral load
applied to the specimen.
Cohesion
Soil deposits that experience significant decrease in volume
when exposed to water.
Collapsible soils
Soils formed by movement of soil from its original place
during landslides. by gravity such as during landslide.
Colluvial soils
Is defined as the process by which the soil particles are
artificially rearranged and packed together into a state of
closer contact by mechanical means in order to decrease its
porosity and thereby increase its dry density.
Compaction
The densification of soil by removal of air, which requires
mechanical energy.
Compaction
It is the slope of the field consolidation line. It is an index
used for calculation of field settlement caused by
consolidation of soil.
Compression index
Refers to the texture and firmness of a soil and is often
directly related to the strength.
Consistency
Is defined as the ratio of the difference between liquid limit
and the natural water content to the plasticity index of a
soil.
Consistency index
A tri-axial test similar to the consolidated undrained test
except that the specimen is allowed to drain as the axial
load is applied so that high excess pore pressures do not
develop. Because the permeability of clayey soils is low, the
axial load must be added very slowly during consolidated
drained test so that excess pore pressure can be dissipated.
Consolidated drained tes
A tri-axial test which is performed by placing the specimen
in the chamber and introducing lateral pressure. The sample
is then allowed to consolidate under the lateral pressure by
leaving the drain lines open. The drain lines are then closed
and axial stress is increased without allowing further
drainage.
Consolidated undrained test
A time dependent settlement of soils resulting from the
expulsion of water from the soil pores. Any volume decrease
of a soil mass.
Constant head tes
Consolidation
Two standard laboratory tests used to determine the
hydraulic conductivity of soil
Constant head test and the falling head test
The pressure acting between a footings base and the soil
below.
Contact pressure
A stress state reached in a soil when continuous shearing
occurs at constant shear stress and constant volume.
Critical state
The void ratio that exists prion to a shearing process in
which the net volume change at failure is zero.
Critical void ratio
Another term for tri-axial test.
Cylindrical compression test
Average particle diameter of soil.
D50
The constant of proportionality, factor that indicates if the
volume of flow is to be great or small, relates to the ease or
difficulty with which the water moves through the soil.
Darcy’s coefficient of permeability
The quantity of water flowing through the soil in a given
period was proportional to the soil area normal to the
direction of flow and the difference in water levels indicated
in the piezometers, and inversely proportional to the length
of soil between piezometers through which flow took place.
Darcy’s Law
Foundation that have a depth of embedment to width ratio
is greater than four (4).
Deep foundation
The ratio of the volume of water to the volume of voids.
Degree of saturation
The ratio of the unconfined compression strength in an
undisturbed state to that in a remolded state.
Degree of sensitivity
A test (also known as water mobility on shaking test)
consists of placing a part of moist soil in the palm of the
hand and then shaking the hand. If a shiny, moist surface
appears on the soil after shaking it in the open hand and
then becomes dull and dry when the pat is squeezed by
closing the hand a non plastic soil (silt) is indicated.
Dilatancy test
A measure of the change in volume of soil when it is
distorted by shearing.
Dilation
A shear test where in the shear box that contains the soil
specimen is generally kept inside a container that can be
filled with water to saturate the specimen.
Direct shear test
The longest vertical path that a water particle will take to
the drainage surface.
Drainage path
A shear test made on saturated soil specimen by keeping
the rate of loading slowly enough so that the excess pore
water pressure generated in the soil is completely dissipated
by drainage.
Drain direct shear test
The weight per unit excluding water volume of soil,
excluding water.
Dry unit weight
A technique used for the densification of granular soil
deposits which consists primarily of dropping a heavy weight
repeatedly on the ground at regular intervals.
Dynamic compaction
Refers to lateral pressure caused by earth that is prevented
from lateral movement by an unyielding wall.
Earth pressure at rest
Is a measure of the shear strength of soil.
Effective friction angle
The average particle diameter of the soil at 10 percentile,
that is 10% of the particles are smaller than this size.
Effective particle size (D10)
A parameter of a soil which indicates the diameter in the
particle size distribution curve corresponding to 10% finer.
Effective size
The weight of soil solids in a submerged soil per unit
volume.
Effective unit weight
It is the depth below the ground surface where the base of
the foundation rests.
Embedment depth
It is one that transfers almost all the structural load to the
soil at the bottom end of the pile.
End bearing or Point bearing pile
A pile that is driven until it rests on a hard, impenetrable
layer of soil or rock, the load of the structure is transmitted
primarily axially through the pile to the impenetrable layer.
End-bearing pile
It is a line representing constant head.
Equipotential line
It is the ratio of the ultimate net bearing capacity to the
allowable bearing capacity or to the applied maximum
vertical stress.
Factor of safety or Safety factor
Types of soil which have at least 50% passing the #200 sieve.
Fine grained soils
