HGE Terms

Void Ratio (e)

Ratio of volume of voids to volume of soil solids.

Porosity (n)

Ratio of volume of voids to total soil volume.

Degree of Saturation (S)

Ratio of volume of water to volume of voids.

Moisture Content (w)

Ratio of weight of water to weight of dry soil solids.

Specific Gravity (Gs)

Ratio of unit weight of soil solids to unit weight of distilled water.

Atterberg Limits

Boundary moisture contents indicating soil consistency transitions (Liquid, Plastic, Shrinkage).

plasticity Index (PI)

Range of moisture content where soil acts plastic ($PI = LL - PL$).

Liquid Limit (LL)

Moisture content at which soil transitions from plastic to liquid behavior.

Plastic Limit (PL)

Minimum moisture content at which soil can be rolled into a 3 mm thread without crumbling.

Unified Soil Classification System (USCS)

Soil classification system based on grain size distribution and Atterberg limits.

Darcy's Law

Soil seepage rate (Q) is proportional to hydraulic gradient ($i$) and permeability ($k$).

Permeability (k)

Ability of soil to allow water to pass through its interconnected voids.

Quick Sand Condition

Condition where effective stress becomes zero due to upward seepage pressure ($i_{cr} = \frac{G_s - 1}{1 + e}$).

Liquefaction

Loss of shear strength in saturated cohesionless soils due to dynamic/earthquake loading.

Consolidation

Gradual time-dependent volume reduction of cohesive soils under load due to expulsion of pore water.

Compaction

Mechanical densification of dry/moist soil by driving out trapped air voids.

Normally Consolidated Soil

Soil currently experiencing its historical maximum overburden pressure.

Overconsolidated Soil

Soil that has previously experienced past overburden pressure higher than current levels.

Shear Strength

Internal resistance per unit area offered by soil to resist failure along a plane.

Cohesion (c)

Interparticle attractive force in clay/fine soils independent of normal stress.

Angle of Internal Friction (phi)

Measure of shear strength resistance derived from particle-to-particle friction/interlocking.

Negative Skin Friction

Downward drag force exerted on piles due to relative downward settlement of surrounding soft soil.

Bearing Capacity

Maximum pressure a soil deposit can support from a foundation without shear failure or excessive settlement.

Terzaghi's Bearing Capacity Theory

Standard method estimating ultimate bearing capacity of shallow foundations.

Flow Net

Graphical representation of two-dimensional seepage consisting of flow lines and equipotential lines.

both moisture content and amount of compaction energy

The maximum dry unit density up to which any soil can be compacted depends upon _____

stress taken up by the pore water

The neutral stress in a soil mass is

Triaxial Test

Standard Penetration Test (SPT)

Unconfined Compressive Test

Direct Shear Test

Standard penetration test (SPT)

Among the methods for determining the shear strength of soils, which test may NOT accurately represent filed conditions?

Direct shear test

What laboratory test is commonly used to determine both cohesion and angle of internal friction?

Triaxial tests

Among the methods for determining the shear strength of soils, which test measures the shear strength of a soil sample under various confining pressure?

Friction angle

Which property of soil increases with an increase in compaction effort?

Sand Cone Method

Which test is commonly used in the Philippines to determine the in-situ density of compacted soil in roadworks?

Pore water cannot drain

Which of the following best describes the reason why saturated clays fail at lower shear strength under rapid loading?

Gravel

What type of soil typically has the highest angle of internal friction?

Poorly graded

A DPWH project requires identifying a soil type for slope stability analysis. The test results show Cu = 2.8 and Cc = 4.2. How will you. describe this soil gradation? See Unified Soil Classification System

Viscosity

Resistance of a fluid to shear stress or flow.

Cohesion (Fluids)

Intermolecular attraction between like molecules (e.g., surface tension).

Adhesion (Fluids)

Attraction between unlike molecules (e.g., fluid sticking to glass).

Capillarity

Rise or fall of liquid in a small tube due to surface tension, cohesion, and adhesion.

Specific Weight

Weight per unit volume of a fluid.

Pascal's Principle

Pressure applied to an enclosed fluid is transmitted undiminished in all directions.

Archimedes' Principle

A submerged body experiences an buoyant force equal to the weight of displaced fluid.

Bernoulli's Principle

Conservation of energy in fluid flow: sum of pressure, kinetic, and potential heads is constant.

Metacenter

Intersection of the vertical line through the center of buoyancy with the vertical axis of a tilted floating body.

Metacentric Height (GM)

Distance from Center of Gravity (G) to Metacenter (M). Determines float stability.

Center of Pressure

Point of application of the total hydrostatic force on a submerged surface.

Laminar Flow

Smooth, parallel-layered fluid movement (Re < 2000 for pipes).

Turbulent Flow

Chaotic fluid movement with eddies and vortices (Re > 4000 for pipes). Its fluid particles vary from point to point in magnitude and direction

Steady Flow

Fluid properties at a fixed point do not change over time. Q same @ any given time

Uniform Flow

Velocity remains constant along the length of the channel/pipe.

Non-uniform Flow

Velocity varies along the length of the channel/pipe.

Water Hammer

High-pressure wave surge caused by a sudden stoppage of fluid flow.

Hydraulic Gradient Line (HGL)

Line representing the sum of elevation head and pressure head.

Energy Grade Line (EGL)

Line representing total head.

Hydraulic Jump

Sudden transition from high-velocity supercritical flow to low-velocity subcritical flow with energy dissipation.

Critical Depth

Water depth in an open channel where total energy is minimum for a given discharge.

Specific Energy

Energy per unit weight of fluid measured relative to the channel bed.

Weir

Obstacle in an open channel used to measure or regulate flow rate.

Piezometer

Vertical tube used to measure small gauge pressures in pipes.

Cavitation

Formation and collapse of vapor bubbles due to localized low pressure, causing surface pitting.

Major Head Loss

Head loss caused by friction along the pipe wall (Darcy-Weisbach / Hazen-Williams).

Orifice

a small aperture through which the fluid passes. (maliit na butas)

Particle size

is the primary factor that LEAST affects the shear strength of the soil?(BE 2026)

This statement about Bernoulli's equation is true (BE 2026)

it assumes no energy loss due to

friction

Piezometers

are used to measure pressure in water channels, pipes, etc.

Dead Sea

In which body of water will a person that more easily sink?

Cohesion

Which of the following parameters is typically zero for dry sand?

Continious Flow

Q is same every section

Unsteady Flow

Q varies @ any given time

Critical Flow

Type of flow in which, for a fixed rate of flow, the specific energy is minimum.

Sub-Critical Flow

Max depth altho mabagal

below the centroid

A gate is inclined at 45" to the horizontal and submerged in water. The center of pressure lies _____.

double

If the depth below a liquid surface is doubled, the hydrostatic pressure will:

Due to buoyant

A balloon filled with hot air has lower density than ambient air. Why does it rise?

12m

A pump must raise water 12 m to a rooftop tank. What minimum pressure head should it provide in meters?

Mass

What is the following quantities is conserved in ideal hydrodynamics flow?

Laminar, Turbulent, Uniform

Which are classifications of flow in fluid mechanics?

at 4°C temperature

The specific weight of water is 1000 kg/m³. To use this value the water must be

1V:2H

According to section 302.2.2 of NSCP, the slope of cut surfaces shall be no steeper than is safe for the intended use and shall be no steeper than: (CE May 2022)

Liquefaction

This occurs when a cohesionless saturated or partially saturated soil substantially loses strength and stiffness in response to an applied stress such as shaking during an earthquake or other sudden change in stress condition, in which material that is ordinarily a solid behaves like a liquid.

Solidification

The process by which a liquid turns into a solid as it cools, usually through freezing.

24 to 48

a cohesive soil deposit is considered soft if the unconfined compression strength, in kPa, is between:

Archimedes

Which of the following states the law of bouyancy

Steady Flow

A flow in which the velocity of the fluid at a particular fixed point does not change with time

Cohesion

Which component of rock or soil is independent of interparticle friction

Liquefaction

A phenomenon in which the stregth and stiffness of a soil is reduced by earthquake shaking or other rapid loading

Effective Stress

A pile of sand keeps from spreading out like a liquid because the weight of the sand keeps the grains stuck together in their current arrangement, mostly out of static friction. This weight and pressure is called.

Gas

Which of the following is not a soil component

Sieve Analysis

A practice or procedure used to asses the particle size distribution (also called gradation) of a granular material. The size distribution is often of critical importance to the way the material performs in use

Gravel

According to USCS, What do you call a soil grain with grain size greater than 4.75mm but less than 75mm?

none of these (location of GWT, depth of backfill, plasticity of the soil)

Which of the following does not affect the settlement of a footing

Cohesion

Molecules of liquid bond together because of?

Energy Gradeline

A line joining the points of the highest elevation of water in a series of vertical open pipes rising from a pipeline in which water flow under pressure is refered to as:

Uncemented aggregates

In civil engineering, soil is described as?

Vane shear test

Which of the following soil shear strength tests is not performed in a laboratory?

Law of conservation of mass

The continuous flow of fluid is based on the law of conservation of?