MAY 2012
Porosity
Decrease of the effective stress The ratio between the vol-
at that point ume of void and the vol-
The ground water table is ume of the soil mass.
located at a certain depth Condition: 0 < n < 100
below the ground surface.
This will cause an upward Moisture Content
seepage. What would be The ratio between the
the resulting effective weight of water and the
stress at a certain point be- weight of solid particles.
low the ground water table
due to the upward seep- 0.064 N/m
age.
The surface tension phe-
Dry unit weight of soil will in- nomenon is one of the
crease reasons that small in-
If we increase the com- sects can walk on water.
paction energy, what will The value of surface
happen to the max. dry tension at normal room
density ( MDD ) ? temperature.
Over Consolidated
It is a soil whose
MAY 2015 present effective
over burn pressure is
Surface Tension less than that which
The elastic tendency of liq- the soil experienced
uids which makes them ac- in the past.
quire the least surface
area possible. It is respon- Decrease of lateral pres-
sible, for example, when sure
an object or insect such as
mosquitoes that is denser It happens when
than water is able to float there is a lowering of
or run along the water sur- water table.
face. Water Content
Degree of Saturation The ratio of the
The ratio between the vol- weight of water to
ume of water and the vol- the weight of solids
ume of voids. in a given volume of
Condition: 0 ≤S ≤100 soil.
Void Ratio
The ratio of the vol- stuck together in their cur-
ume of voids to the rent arrangement, mostly
volume of solids. out of static friction.
The most used prop- Gas
erty in soil proper- Not a soil component.
ties. (Components of soil are
Condtion: 0 < 100 organic materials, miner-
als, etc.)
Sieve Analysis
A practice procedure used
NOVEMBER 2015 to assess the particle size
distribution (also called
Archimedes gradation) of a granular
A body placed in a liquid is material. The size distribu-
buoyed up by a force equal tion is often called of criti-
to the weight of the dis- cal importance to the way
placed liquid. the material performs in
use.
Steady Flow
A flow in which the dis- Gravel
charge passing a given According to USCS, is a
cross-section of a stress is soil grain with grain size
constant with time greater than 4.75 mm but
Cohesion less than 75 mm. (75 mm
The component of shear > 4.75 mm)
strength of a rock or soil
that is independent of in- Boulders
terparticle friction. Particles of rock that will
not pass a 12 in (200 mm)
Liquefaction sieve. (200 mm < …)
A phenomenon in which
the strength and stiffness Cobble
of a soil is reduced by Particles of rock that will
earthquake shaking or pass a 12 in (300 mm)
other rapid loading. square opening and be re-
A process by which water- tained on a 3 in (75 mm)
saturated soil sediment sieve. (300 mm > 75 mm)
temporarily loss strength
and acts as a fluid Coarse Aggregate
(75 mm > 19 mm) passes
Effective Stress 3 in (75 mm) sieve and re-
A pile of sand keeps from tains ¾ in (19 mm) sieve.
spreading out like a liquid
because the weight of the Fine Aggregate
sand keeps the grains
(19 mm > 4.75 mm) In accordance with the
passes ¾ in (19 mm) sieve Unified Soils Classification
and retains No. 4 (4.75 of Soils, which are consid-
mm) sieve. ered coarse grained if the
passing thru No. 200 sieve
Settlement of Footing is less than __________.
Location of GWT, depth of
backfill, and plasticity of
soil affects the settlement Uniform flow
of footing. If with steady flow in any
length or reach of a
1:2 stream, the average veloc-
Section 302.4.5 of the Na- ity at every cross-section is
tional Structural Code of the the same in that reach, the
Philippines (C101-10) pro- flow is said to be :
vides that slope of fill sur-
face shall be no steeper
Above the center of gravity
than is safe for its intended
use and shall not be A ship floating in seawater
steeper than is stable if the metacentric
height is:
0.50
The cohesion Strength of a Discharge
cohesive soil is a compres-
sion strength, C = k.qu. The volume of liquid pass-
Where k is equal to ing a cross-section of a
_____? stream.
Shear
MAY 2016
Soil derives its strength
from its capacity to resist Turbulent Flow
______. When the path lines of the
individual particles of a
1 to 2 flowing liquid are irregular
Section 302.2.2 of the Na- curves and continually
tional Structural Code of cross each other and form
the Philippines provides a complicated network.
that the slope of Cut sur-
faces shall be no steeper Hydraulic Gradient
than is safe for intended A line joining the points of
use and shall be no highest elevation of water
steeper than ______. in a series of vertical open
pipes rising from a pipeline
50 in which water flows under
pressure.
Water Hammer
A pressure surge or wave
caused when a fluid in mo- Atterberg Limit Test (No. 40
tion is forced to stop or Sieve)
change direction suddenly For determining the Atter-
(momentum change). berg limit (plastic and liquid
limits), the soil sample
must pass through a 0.425
mm sieve.
24 to 48 MAY 2018
A cohesive soil deposit is
considered soft if the un- 10 – 30
confined compression A granular soil deposit is consid-
strength in kPa is between: ered medium if the blow count of a
standard penetration is between
40
Prone to Settlement under
NOVEMBER 2016 vibratory load
4°C High Shear Strength
Temperature at which liq- One of the following is not
uid water has the highest Characteristic of cohesion-
density. less soils:
Pascal’s Principle
A principle of mechanics
that the pressure exerted NOVEMBER 2019
onto a liquid is transmitted
equally and undiminished
to all portions of the liquid.
Continuous Flow
When at any instant, the
Bernoulli’s Principle number of particles pass-
A principle that in any ing every section of the
stream flowing steadily stream are always equal,
without friction, the total the flow is said to be .
energy contained is the
same at every point in its
path of flow. NOVEMBER 2021
0.0740 mm
Decrease in the Vertical Pres-
The largest grain size that
passes a no. 200 sieve in sure
millimeters is ________. What would happen if the
ground water table will be at
MAY 2017 the ground level ?
Decrease consists of four equal-
sized thin steel plates
If the ground water table in welded to a steel torque
a soil formation rises as a rod. The vane is pushed
resulting of flooding, the into the soil and torque
bearing capacity of the ( T ) is applied at the top of
soil_______. the torque rod to rotate the
vane at a uniform speed to
cause failure.
Load imposed onto the soil
One of the following foun- Hydrodynamics
dation conditions does not A branch of hydraulics
affect the bearing capacity which deals with the study
of the supporting soil. of forces (including velocity
and acceleration) exerted
by or upon liquids in mo-
tion.
NOVEMBER 2022
Hydraulic Jump
Shear Vane An abrupt rise in water sur-
It is a device used to deter- face which results from re-
mine the undrained shear tarding water flowing at
strength of the soil which lower stage
APRIL 2023
The shear strength of a soil increases with increase in normal stress.
Triaxial shear test acts on all plane axes except x and y axis.
In what plane is the additional stress (deviator stress) can affect the
shear stress? Horizontal.
Vane Test is a test not performed in a laboratory.
In AASHTO, soil greater than 75 mm is classified as cobbles.
In 1.3cNc + qNq + 0.4BɣNɣ, Nc, Nq and Nɣ are function of angle of
friction.
When molecules get attracted to others it is called cohesion.
Where is the metacenter for stable equilibrium? Above center of grav-
ity.
If the volume of voids is equal to the volume of solids, what is the
porosity and void equal to respectively? 0.5 and 1.0.
The shear strength of a cohesionless soil is proportional to the tangent
of the angle of shearing resistance.
The intensity of vertical stress at a depth due to a point load acting on
the surface of a semi-infinite elastic soil mass is directly proportional to
the square of depth.
When the metacenter of a floating body is lower than the center of
gravity, then the body will be in unstable equilibrium.
The metacentric height is the distance between the center of the grav-
ity of the floating body and the metacenter.
Negative skin friction on piles caused by soft clay, decreases the pile
capacity and due to relative settlement of soil.
Specific weight of liquid does not vary on any other planet.
In civil engineering, soil is a structural material or uncemented aggre-
gate.
The weight per unit volume of a liquid at a standard temperature and
pressure is called specific weight.
dropping through a height
of h"
Velocity Head
The difference between
the hydraulic grade line
and energy grade line is.
Aquifers
Deep groundwater de-
posits where underground Critical flow
water are available for wa- A type of open channel
ter supply and irrigation flow where the Froude
Number is equal to 1
Laminar
In a fluid flow, if the fluid Open channel flow
travels parallel to the adja- It is defined as a conduit in
cent layers and the paths which the liquid flows with
of individual particles do a free surface subjected to
not cross atmospheric pressure. The
flow is caused by the slope
Turbulent of the conduit and the liq-
A condition of flow charac- uid surface:
terized when fluid particles
move in very irregular Weir
paths, causing an ex- It is an overflow structure
change of momentum for built across an open chan-
portion of the liquid to an- nel for the purpose of mea-
other is. suring or controlling the
flow.
Bernoulli Principle
A principle of flow mea- Hydrometer Analysis
surement which states that Is the test used to deter-
the increase in kinetic en- mine the grain size distri-
ergy per unit weight is bution of the soils passing
equal to the decrease in the No. 200 sieve.
the potential energy per
unit weight Hazen's Effective Size
It is the grain size corre-
Torricelli Law sponding to 10 percent
"The theoretical velocity of passing on a grain-size
a jet of liquid issuing out of distribution curve.
an orifice under a head of
h being equal to the veloc- Relative density
ity of a free-falling body Is the ratio of the differ-
ence between the void ra-
tios of a cohesionless soil
in its loosest state and ex- Plasticity
isting natural state to the Degree a soil can be
difference between its void molded or reworked caus-
ratio in the loosest and ing permanent deformation
densest states without rupturing.
Liquid limit
Is defined as the moisture
content at which soil be-
Soil Consistency gins to behave as a liquid
Provides a means of de- material and begins to
scribing the degree and flow.
kind of cohesion and adhe-
sion between the soil parti- Plastic limit
cles as related to the resis- Is defined as the moisture
tance of the soil to deform content at which soil be-
or rupture. gins to behave as a plastic
material: It is also defined
Rupture Resistance as the moisture content at
It is a field measure of the which the soil crumbles
ability of the soil to with- when rolled into a thread of
stand applied stress or 3.18 mm in diameter.
pressure as applied using
the thumb and forefinger. Shrinkage Limit
Is defined as the moisture
Cohesion content at which no further
Is the attraction of one wa- volume change occurs with
ter molecule to another re- further reduction in mois-
sulting from hydrogen ture content.
bonding (water-water
bond). Compaction
Is the densification of soil
Adhesion by removal of air, which re-
It involves the attraction of quires mechanical energy.
a water molecule to a non-
water molecule (water- Optimum Moisture Content
solid bond). The moisture content at
which the maximum dry
Stickiness unit weight of soil is at-
The capacity of soil to ad- tained
here to other objects. It is
estimated at moisture con- Vibroflotation
tent that displays maxi- It is a technique for in situ
mum adherence between densification of thick layers
thumb and forefinger.
of loose granular soil de- Secondary consolidation settle-
posits. ment
The result of the plastic ad-
Equipotential Line justment of soil fabrics.
A line along which the po-
tential head at all points Shear strength
are equal. The internal resistance per
unit area of the soil mass
Flow line to resist failure and sliding
A line along which water along any plane.
particle will travel from up-
stream to the downstream
side in the permeable soil
medium. Overconsolidation ratio (OCR)
Ratio of preconsolidation
Flow Nets pressure to present effec-
They are constructed to tive overburden pressure.
calculate the groundwater Unrestrained Slope
flow in the media that com- An exposed ground sur-
bine flow line and equipo- face that stands at an an-
tential lines. gle with the horizontal. It is
a slope that can either be
Effective Stress natural or constructed.
The sum of the vertical
components of the forces Subsurface Exploration
developed at the points of The process of identifying
contact of the solid parti- the layers of deposits that
cles per unit cross sec- underlie a proposed struc-
tional area of the soil ture and their physical
mass. characteristics:
Immediate settlement Method of Slices
Caused by the elastic de- It is a method for analyzing
formation of dry soil and of the stability of a slope in
moist and saturated soils two dimensions.
without any change in the
moisture content. Base Failure
It is a type of failure that
Primary consolidation settle- occurs in such a way that
ment the surface of sliding
The result of volume passes at a distance below
change in saturated cohe- the toe of the slope.
sive soils because of the
expulsion of water that oc- Slope failure
cupies the void spaces. It is a type of failure that
occurs in such a way that
the surface of sliding inter- The state occurs when a
sects the slope or above soil mass is allowed to re-
its toe. lax or move outward to the
point of reaching the limit-
Toe Circle ing strength of the soil; that
It is the failure circle in the is, the soil is at the failure
case of slope and occurs condition in extension.
when it passes through the
toe of the slope. Spread Footing
It is simply an enlargement
of a load bearing wall or
column that makes it pos-
sible to spread the load of
the structure over the large
Slope Circle area of the soil.
It is the failure circle in the Pile
case of slope circle and It is a structural member
occurred when it passes made of concrete, timber,
above the toe of the slope or steel that transmit the
load of the superstructure
Mid-point Circle to the lower layers of the
It is the failure circle in the soil.
case of base failure.
Mat Foundation
Plastic Equilibrium It is a type of foundation
It refers to the condition in which is referred to as a
which every point in a soil raft foundation: It is a com-
mass is on the verge of bined footing that may
failure cover entire area under
structure supporting sev-
Lateral Earth Pressure eral columns and walls.
It is the pressure that soil
exerts against a structure Terzaghi
in a sideways, mainly hori- He was the first to present
zontal direction. The com- a comprehensive theory
mon applications of its the- for evaluating the ultimate
ory are for the design of bearing capacity of rough
ground engineering struc- shallow foundation. Ac-
tures such as retaining cording to his theory the
walls, basements, tunnels, depth of the foundation is
and to determine the fric- shallow if the depth of the
tion on the sides of deep foundation is less than or
foundations. equal to the width of the
foundation.
Active State
Meyorhof
He proposed a correlation N will penetrate a distance
for the net allowable bear- d=20 mm in 5 seconds
ing pressure for foundation when allowed to drop from
with the standard penetra- a position of point contact
tion resistance. with the soil surface.
Gravity Retaining Wall Archimedes’ principle
It is a type of retaining wall The resultant upward pres-
which is constructed with sure of a fluid on a floating
plain concrete or stone body is equal to the weight
masonry. They depend on of the fluid displaced by
their own weight and any the body.
soil resting on the masonry Principle involved in the re-
for stability and it is not lationship between sub-
economical for high walls. merged unit weight and
Cantilever Retaining Wall saturated unit weight of a
They are made up of rein- soil
forced concrete that con-
sist of a thin stem and a Buoyant force
base slab. This type of wall The resultant upward pres-
is economical to a height sure of the fluid on an im-
of about 8m. mersed body
Counterfort Retaining Wall Displacement of fluid due to
It is similar to the Can- submerged body
tilever Retaining Wall; its The principal cause of ac-
purpose is to reduce the tion of buoyant force on a
shear and the bending mo- body submerged partially
ments. or fully in fluid.
Degree Of Sensitivity Center of buoyancy
It is defined as the ratio of The center of gravity of the
the unconfined compres- volume of the liquid dis-
sion strength in an undis- placed by an immersed
turbed state to that in a re- body.
molded state
Zero
Fall Cone Test The horizontal component
It is another method of de- of buoyant force.
termining liquid limit that is
popular in Europe and in Centroid of the displaced vol-
Asia. In this test the liquid ume of fluid
limit is defined as the mois- The line of action of the
ture content at which a buoyant force acts through
standard cone of apex an-
gle 300 and weighing 0.78 By altering the shape.
How can relatively denser
objects be made to float on Linear
the less dense fluid? The variation of total pres-
sure with depth for any
Potential, kinetic and pressure submerged surface if we
heads neglect variation in the
Energy gradient line takes density.
into consideration
Potential and pressure heads Loam
only Mixture of sand, silt, and
Hydraulic gradient line clay size particles in ap-
takes into consideration
proximately equal propor-
Kinetic head tions.
It is equal to the vertical in-
tercept between EGL and Soil
HGL. The unaggregated and
uncemented deposits of
Bernoulli equation minerals and organic
It deals with the law of con- particles covering the
servation of Energy. earth’s crust
Equation of continuity
It is based on the principle
of conservation of Mass.
Cohesion
Property of a fluid by which
its own molecules are at-
tracted
Adhesion
Property of a fluid by which
molecules of different
kinds of fluids are attracted
to each other.
Center of pressure
The point in the immersed
body through which the re-
sultant pressure of the liq-
uid may be taken to act.
Below the centroid
It is where the center of
pressure on an inclined
plane.
In the unit phase diagram for a soil mass: The volume of solids is taken
as unity
Rise of water table above the ground surface causes: Equal in-
crease in pore water pressure and total stress
