Civil Engineering Terminologies Review

A comprehensive set of question-and-answer flashcards covering civil engineering terms and concepts drawn from the provided lecture notes, including geotechnical, structural, hydraulic, material, and transportation topics.

What is surface tension in fluids?

The elastic tendency of liquids that makes them acquire the least surface area possible.

What is the degree of saturation of a soil?

The ratio between the volume of water and the volume of voids in the soil.

Define soil porosity.

The ratio between the volume of voids and the total volume of the soil mass.

What is soil moisture content?

The ratio of the weight of water to the weight of solid particles in a soil sample.

Which law explains buoyancy?

Archimedes’ principle.

What characterizes a steady flow of fluid?

Velocity at a fixed point does not change with time.

In soil mechanics, what is cohesion?

The component of shear strength that is independent of inter-particle friction.

What is liquefaction?

Loss of soil strength and stiffness due to rapid loading such as earthquake shaking.

In geotechnical terms, what is effective stress responsible for?

Keeping sand grains pressed together so the pile retains shape instead of flowing like a liquid.

Which state of matter is NOT a soil component?

Gas.

What does a sieve analysis determine?

The particle size distribution (gradation) of a granular material.

According to USCS, what particle size range defines gravel?

Greater than 4.75 mm and less than 75 mm.

What rock particles are classified as boulders?

Particles that will NOT pass a 200 mm (≈12 in) opening.

What size range defines cobbles in AASHTO?

Particles larger than 75 mm but passing a 300 mm square opening.

Define coarse aggregate by sieve sizes.

Passes 75 mm (3 in) sieve and is retained on 19 mm (¾ in) sieve.

Define fine aggregate by sieve sizes.

Passes 19 mm (¾ in) sieve and is retained on No. 4 (4.75 mm) sieve.

Name three factors that affect footing settlement.

Ground-water table location, depth of backfill, and soil plasticity.

What maximum slope is allowed for a fill or cut?

1 vertical : 2 horizontal (1:2).

Describe turbulent flow.

Liquid particle paths are irregular, crossing, and form a complicated network.

What is a hydraulic gradient line?

A line joining highest water elevations in open pipes connected to a pressurized pipeline.

What is the water-hammer phenomenon?

A pressure surge when a moving fluid stops or changes direction suddenly.

At what unconfined compressive strength (kPa) is cohesive soil ‘soft’?

0 – 24 kPa.

At what temperature does liquid water reach maximum density?

4 °C.

State Pascal’s principle.

Pressure applied to a confined liquid is transmitted equally and undiminished in all directions.

State Bernoulli’s principle for frictionless steady flow.

The total energy per unit weight is constant at every point along the streamline.

Which sieve is used for Atterberg limits tests?

No. 40 (0.425 mm) sieve.

Give two key characteristics of cohesionless soil.

Easy to compact, high shear strength (but prone to vibration-induced settlement).

What SPT N-value indicates medium-dense sand?

10 – 30 blows/300 mm penetration.

How does normal stress affect soil shear strength?

Shear strength increases with increasing normal stress.

Which plane is affected by deviator stress in triaxial tests?

The horizontal plane.

Is the vane shear test done in the lab or field?

Field (not performed in a laboratory).

In AASHTO, soil >75 mm is classified as what?

Cobbles.

In Terzaghi’s bearing-capacity equation, on what do Nc, Nq, and Nγ depend?

They are functions of the soil’s angle of internal friction (φ).

Where must the metacenter be for stable equilibrium of a floating body?

Above the center of gravity.

If volume of voids equals volume of solids, what is porosity n?

0.5 (and void ratio e = 1.0).

On what is shear strength of cohesionless soil proportional?

tan φ, the tangent of the angle of shearing resistance.

How does vertical stress beneath a point load vary with depth in elastic soil?

Directly proportional to 1/(depth)² (Boussinesq equation).

What happens if the metacenter is lower than the center of gravity?

The floating body is in unstable equilibrium.

Define metacentric height.

Distance between center of gravity and metacenter of a floating body.

What causes negative skin friction on piles?

Settlement of soft surrounding clay relative to the pile, decreasing capacity.

Define orthotropic material.

Same composition but mechanical properties differ in three orthogonal directions.

What is an isotropic material?

Materials whose stress-strain response is independent of orientation at a point.

What is material toughness?

Ability to absorb energy in the plastic range before fracturing.

Define resilience of a material.

Ability to absorb energy in the elastic range and release it on unloading.

What is ductility?

Capacity to deform plastically without breaking.

What is center of rigidity in a structure?

Point through which resultant of lateral resistance acts.

What structural stress arises when CM and CR do not coincide?

Torsional shear stress.

Define soft storey.

A floor less than 70 % as stiff as the floor above or <80 % of the average stiffness of the three floors above.

What is storey drift?

Lateral displacement of one floor relative to the floor above or below.

What formula gives total stiffness of two parallel springs?

k = k₁ + k₂.

What is inverse of stiffness commonly called?

Flexibility.

Define significant wave height.

Average height of the highest one-third of waves in a wave train.

What is a seiche?

A standing wave in an enclosed or partially enclosed water body caused by wind or pressure changes.

Describe wind sea.

Waves directly generated and influenced by local wind.

What is a caisson in construction?

A watertight box-like structure used for underwater construction work.

Define shoring.

Temporary supports used to stabilize structures or excavations during construction.

What is the purpose of a pier?

Raised platform extending over water for docking or loading/unloading vessels.

What type of traffic sign gives route and service information?

Guide sign.

What is traffic delay?

Difference between actual travel time and ideal travel time over a road segment.

Describe alligator cracking.

Interconnected fatigue cracking in asphalt caused by aging, heavy loads, or poor drainage.

Define transverse cracks in pavement.

Cracks roughly perpendicular to centerline due to shrinkage or thermal stress.

What is screeding in concrete work?

Leveling freshly placed concrete with a straightedge.

When is floating performed?

After screeding, to remove imperfections and consolidate the surface.

What is concrete trowelling for?

Smoothing and densifying the surface after floating.

Define age of tides.

Time (up to ~2.5 days) between syzygy (new/full moon) and the highest local tide.

What is a diurnal tide pattern?

One high tide and one low tide each lunar day (24 h 50 min).

Define semi-diurnal tide.

Two nearly equal high tides and two low tides each lunar day.

What is raveling in asphalt pavement?

Progressive loss of aggregate particles from the surface.

What is bleeding in asphalt?

Upward migration of asphalt binder forming shiny film on surface.

What is concrete batching?

Proportioning cement, water, aggregates, and additives before mixing.

Purpose of a slump test?

To measure the consistency/workability of fresh concrete.

Why is water-cement ratio critical?

It governs concrete strength and durability.

What process increases soil density by expelling water from voids?

Consolidation.

Which committee reviews safety inspection and accident reports on a project?

Health and Safety Committee.

What is grouting in geotechnics?

Injecting material into soil/rock to improve strength or reduce water flow.

In bolt design, when calculating maximum safe load, what value of P is used?

The least (minimum) value of load capacity.

For column slenderness checks, which slenderness ratio governs allowable load?

The greatest (largest) slenderness ratio.

What is specific weight?

Weight per unit volume of a fluid at standard temperature and pressure.