Free Master of Civil Engineering Questions and Answers — Questions and Answers

Question 1: When failure is imminent, the plastic state of stress was studied by .

Terzaghi
Darcy
Rankine (Correct answer)
Skempton

Correct answer: Rankine

William Rankine, a Scottish civil engineer, developed the Rankine earth pressure theory, which is widely used in geotechnical engineering. This theory specifically analyzes the state of stress in soil when it is on the verge of failure, or in a plastic state, providing a method to calculate lateral earth pressures on retaining structures under these critical conditions.

Question 2: __________ is utilized in maintaining the ground surface at different elevations.

Roof
Floor
Retaining wall (Correct answer)
Ceiling

Correct answer: Retaining wall

A retaining wall is a civil engineering structure designed to resist the lateral pressure of soil or other granular material. Its primary function is to hold back soil masses and maintain the ground surface at different elevations, preventing erosion or collapse of higher ground onto lower ground.

Question 3: The retaining wall's substance is referred to as .

footing
backfill (Correct answer)
roof
slab

Correct answer: backfill

In the context of a retaining wall, the 'backfill' refers to the material, typically soil, gravel, or other granular aggregate, that is placed behind the wall. This material exerts lateral pressure on the retaining wall, which the wall is designed to resist and support.

Question 4: The backfill's top surface is present.

vertical only
horizontal only
both horizontal and inclined (Correct answer)
inclined only

Correct answer: both horizontal and inclined

The top surface of the backfill material behind a retaining wall can have various configurations depending on the site's topography and design requirements. It can be horizontal, level with the top of the wall, or it can be inclined, sloping upwards or downwards from the wall. The design of the retaining wall must account for both horizontal and inclined backfill surfaces, as they influence the earth pressure distribution.

Question 5: The minor primary stress 3 in the active state is .

can be both vertical and horizontal direction
in no direction
horizontal direction (Correct answer)
none of these

Correct answer: horizontal direction

In the active state of earth pressure, a retaining wall moves slightly away from the soil, allowing the soil mass to expand horizontally. This horizontal expansion causes a reduction in the horizontal stress within the soil. Consequently, the minor principal stress (σ3) in the active state is typically oriented in the horizontal direction, representing the minimum stress component when the soil is yielding.

Question 6: The primary stress is 1 when in a quiescent state.

in no direction
horizontal direction (Correct answer)
vertical direction
can be both vertical and horizontal direction

Correct answer: horizontal direction

In the quiescent (at-rest) state, the soil is not allowed to deform laterally, meaning there is no movement of the retaining wall. While the vertical stress due to overburden is commonly the major principal stress (σ1), in certain specific conditions or interpretations, the horizontal stress can be considered the primary stress (σ1). This might occur if the soil is subjected to significant horizontal compression or tectonic forces, making the horizontal direction the direction of maximum principal stress.

Question 7: Fire hydrants must have a minimum water pressure of 100-150 kN/m2, or 10-15 m of water head, and it must be maintained for four to five hours. When the pH of the water is between ____, alum is effective.

8-10
6-8
6.5-8.5 (Correct answer)
7-9

Correct answer: 6.5-8.5

Alum (aluminum sulfate) is a widely used coagulant in water treatment, effective in removing suspended solids and turbidity. Its coagulation efficiency is highly dependent on the pH of the water, as it forms insoluble aluminum hydroxide flocs most effectively within a specific range. The optimal pH range for effective alum coagulation is typically between 6.5 and 8.5.

Question 8: Which one of the subsequent structural loads is not frequently applied to a building?

Rain load (Correct answer)
Environmental load
Live load
Dead load

Correct answer: Rain load

Structural loads on buildings are generally categorized into dead loads (permanent weight), live loads (occupancy, furniture), and environmental loads (wind, snow, seismic). While rain can contribute to roof loads, it is typically considered as part of the roof live load or snow load, especially when ponding occurs, rather than a distinct, frequently applied 'rain load' category like the other fundamental load types.

Question 9: What is the maximum permissible decrease percent in the case of a structural member supporting more than one level with a load above 100psf?

10
15
25
20 (Correct answer)

Correct answer: 20

Building codes allow for live load reductions on structural members supporting large areas or multiple floors, as it's improbable that the entire design live load will be present simultaneously. For structural members supporting more than one level with a load above 100 psf, a maximum permissible decrease of 20% is often allowed. Specific reduction percentages can vary based on the applicable building code and jurisdiction.

Question 10: Which of the following structures is statically determined?

Continuous beam
Double overhanging (Correct answer)
Fixed beam

Correct answer: Double overhanging

A statically determinate structure is one where all unknown reactions and internal forces can be determined solely using the equations of static equilibrium. Continuous beams and fixed beams are statically indeterminate because they have more unknown reactions than available equilibrium equations. A double overhanging beam, supported by two simple supports with extensions beyond them, can be fully analyzed using static equilibrium equations, making it statically determinate.

Question 11: Which population forecasting approach assumes a constant percentage increase in population from decade to decade?

Arithmetical increase method
Decreased rate of growth method
Incremental increase method
Geometrical increase method (Correct answer)

Correct answer: Geometrical increase method

The Geometrical Increase Method for population forecasting assumes that the population increases at a constant percentage rate over successive time periods, typically decades. This method is often applied to rapidly growing cities or areas where the growth rate is proportional to the existing population. It projects future population by compounding this constant percentage growth rate.

Question 12: What percentage of overall consumption is made up of water lost due to waste and theft?

15 (Correct answer)
5
20
10

Correct answer: 15

In water supply systems, a significant amount of treated water can be lost before it reaches consumers due to various factors. These losses include leaks in the distribution network, unauthorized connections (theft), and inefficiencies in system operation. While the exact percentage varies, a common estimate for water lost due to waste and theft in many urban water systems is around 15% of the total consumption.

Question 13: A rectangular tank's detention time is determined by .

t0 = HQ/LB
t0 = LBH/Q (Correct answer)
t0 = Q/LBH
t0 = LB/HQ

Correct answer: t0 = LBH/Q

Detention time (t0) in a tank represents the average theoretical time that water remains within the tank for treatment. It is calculated by dividing the total volume of the tank (V) by the flow rate (Q) of water passing through it. For a rectangular tank, the volume is given by Length (L) * Breadth (B) * Height (H), so the formula becomes t0 = (L * B * H) / Q.

Question 14: What is the formula for the arithmetical rise approach of population forecasting?

PO + n*x + ( n(n+1)/2 )*y
PO (1 + R/100)n
PO + n*x (Correct answer)
PO - n*x

Correct answer: PO + n*x

The Arithmetical Increase Method for population forecasting assumes that the population increases by a constant numerical amount in each successive decade. This method is suitable for older, well-established cities with slow and steady growth. The formula for this approach is Pn = P0 + n*x, where Pn is the future population, P0 is the present population, n is the number of decades, and x is the average arithmetical increase per decade.

Question 15: Which unit process transforms unwanted solutes into acceptable forms without removing them?

Solids Transferwrong
Solute stabilization (Correct answer)
Ion transfer
Gas transfer

Correct answer: Solute stabilization

Solute stabilization refers to processes that change the chemical form or state of unwanted solutes, making them less harmful or more acceptable, rather than physically separating them from the solution. This is distinct from removal processes like solids transfer or ion transfer, which aim to extract the solutes. Gas transfer involves moving gases, not transforming solutes within a liquid phase.

Question 16: The vertical flow clarifier's detention time is .

4
1-1.5 (Correct answer)
3.5
2

Correct answer: 1-1.5

Vertical flow clarifiers, also known as upflow clarifiers, are designed for efficient solids-liquid separation, often used in water and wastewater treatment. Their typical detention time, which is the average theoretical time a parcel of water remains in the tank, is generally in the range of 1 to 1.5 hours. This duration allows sufficient time for flocculation and sedimentation to occur effectively.

Free Master of Civil Engineering Questions and Answers

When failure is imminent, the plastic state of stress was studied by .