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Past Questions — 2024
Hydrograph is a graphical representation of -
A)
Surface runoff
B)
Groundwater flow
C)
Rainfall
D)
None of these
A hydrograph is a graph showing the rate of flow (discharge) versus time past a specific point in a river, channel, or catchment. It represents the response of a watershed to a rainfall event. Specifically, it plots the surface runoff (discharge) resulting from precipitation.
- Option (a) is correct because the hydrograph specifically tracks the discharge of surface runoff over time.
- Option (b) is incorrect because groundwater flow is typically analyzed via potentiometric maps or groundwater hydrographs (which are different from the standard storm hydrograph used in surface hydrology).
- Option (c) is incorrect because a graphical representation of rainfall over time is called a 'Hyetograph'.
- Option (d) is incorrect as option (a) is the standard definition.
____ occurs along a long surface parallel to the slope, at some depth.
A)
Rotational failure
B)
Translation failure
C)
Wedge failure
D)
Combined failure
In soil mechanics and slope stability analysis, failures are categorized based on the geometry of the slip surface:
1. **Translational Failure (Option b):** This occurs when the failure surface is planar or nearly planar and runs parallel to the slope surface. It typically happens in soils with distinct weak layers or in rock masses with bedding planes or joints parallel to the slope. The mass of soil slides downward along this parallel surface.
2. **Rotational Failure (Option a):** Also known as a 'slip circle' failure, this occurs when the failure surface is curved (concave). It is most common in homogeneous, fine-grained soils (like clays).
3. **Wedge Failure (Option c):** This occurs when a block of soil or rock slides along two intersecting planes of weakness, creating a wedge-shaped mass. This is common in jointed rock masses.
4. **Combined Failure (Option d):** This is a complex failure mode where the slip surface consists of both rotational and translational segments (e.g., a curved top and a flat base).
Since the question specifically describes a failure occurring along a 'long surface parallel to the slope', it describes a translational failure.
The transition from debris slide to debris flow depends on the
A)
Water content
B)
Size of rock
C)
Depth of soil
D)
Hardness of rock
In geotechnical engineering and geomorphology, a debris slide is a mass movement where the material moves as a relatively coherent block or along a distinct failure plane. A debris flow, however, is a fluid-like movement of saturated soil and rock debris. The critical factor that triggers the transition from a slide (solid-like behavior) to a flow (fluid-like behavior) is the increase in water content. High water content increases the pore water pressure, which reduces the effective stress and the shear strength of the material, effectively 'lubricating' the mass and allowing it to behave as a viscous fluid. While rock size and hardness influence the composition of the debris, they do not dictate the physical transition from sliding to flowing; the saturation level (water content) is the primary driver of this phase change in mass wasting processes.
Gravity type retaining wall primarily mobilise active earth pressure by -
A)
The free deflection at the top
B)
The free deflection at the base
C)
Uniform translation
D)
Sudden overturning
In soil mechanics, Rankine's and Coulomb's theories for active earth pressure state that for the soil to reach its active state (where the lateral pressure is at its minimum), the retaining wall must move away from the backfill. For a gravity retaining wall, which is a rigid structure, this movement occurs primarily as a small rotation about the base. This rotation results in a horizontal displacement (deflection) at the top of the wall. Even a very small amount of movement (typically 0.001H to 0.004H, where H is the height) is sufficient to mobilize the full active earth pressure.
- Option (b) is incorrect because the base is generally constrained by friction and bearing capacity; it does not 'deflect' freely to mobilize pressure.
- Option (c) is incorrect because uniform translation is not the primary mode of movement for a gravity wall; it typically tilts.
- Option (d) is incorrect because 'sudden overturning' refers to a failure state, not the mechanism used to mobilize the design active pressure.
The maximum water content at which a reduction in water content will not cause a decrease in the volume of a soil mass is called -
A)
Plasticity index
B)
Consistency index
C)
Liquid limit
D)
Shrinkage limit
In soil mechanics, the Atterberg limits describe the consistency of fine-grained soils. The Shrinkage Limit (SL) is specifically defined as the maximum water content at which a reduction in water content will not cause a decrease in the volume of the soil mass. When a soil is saturated and its water content is reduced, the soil volume decreases until it reaches the shrinkage limit. Beyond this point, the soil is no longer fully saturated, and further drying does not result in a decrease in volume because the soil particles are already in close contact.
Why other options are incorrect:
- a. Plasticity Index (PI): This is the numerical difference between the liquid limit and the plastic limit (PI = LL - PL), representing the range of water content over which the soil remains plastic.
- b. Consistency Index (CI): This is a ratio that indicates the relative consistency of a soil in its natural state compared to its liquid and plastic limits.
- c. Liquid Limit (LL): This is the water content at which soil transitions from a plastic state to a liquid state.
The failure of a pile foundation is due to -
A)
General shear
B)
Local shear
C)
Mixed shear
D)
Punching shear
In soil mechanics and foundation engineering, the failure modes of shallow foundations (like spread footings) are typically categorized as General Shear, Local Shear, and Punching Shear based on the soil's compressibility and density. However, when considering the failure of a pile foundation—specifically in the context of the pile pushing into the bearing stratum or the soil failing beneath the pile tip—the failure is characterized by 'Punching Shear'.
1. General Shear Failure: Occurs in dense sands or stiff clays where a well-defined failure plane extends to the ground surface. This is typical of shallow foundations on dense soil.
2. Local Shear Failure: Occurs in medium-dense soils where failure planes do not reach the surface.
3. Punching Shear Failure: Occurs in loose sands or soft clays where the foundation (or pile tip) penetrates vertically into the soil with very little disturbance to the surrounding soil mass. Because piles are slender elements that transfer loads deep into the ground, their ultimate bearing capacity failure at the tip in soft/loose soils is a classic example of punching shear.
Therefore, among the given options, punching shear is the characteristic failure mode associated with the penetration of a pile into the soil.
Unconfined compression test is generally performed on -
A)
Sandy soils
B)
Silty soils
C)
Intact saturated clay
D)
Fissured clay
Unconfined compression test (UCT) is generally performed on intact saturated clay because such soils can stand without lateral support during specimen preparation and testing, and the test is specifically used to determine the undrained compressive strength of cohesive soils. Sandy soils and silty soils are not suitable because they are cohesionless or weakly cohesive and cannot usually retain a free-standing cylindrical specimen. Fissured clay is also unsuitable because fissures disturb the specimen and give unreliable strength values.
Darcy’s law of linear dependency between velocity of flow ‘v’ and hydraulic gradient ‘i’ is valid only for -
A)
Laminar flow
B)
Turbulent flow
C)
Fluid
D)
Both (a) & (b)
Darcy's Law is expressed as v = ki, where 'v' is the discharge velocity, 'k' is the coefficient of permeability, and 'i' is the hydraulic gradient. This law establishes a linear relationship between velocity and gradient. For this linear relationship to hold true, the flow of water through the porous medium must be laminar (where the Reynolds number is typically less than 1 to 10). In laminar flow, the viscous forces dominate, and the velocity is directly proportional to the pressure drop. If the flow becomes turbulent (high velocity or very coarse materials), the relationship becomes non-linear, and the velocity increases at a rate different from the hydraulic gradient, rendering Darcy's Law invalid. Therefore, option (a) is correct, and option (b) is incorrect.
In coursed rubble masonry, the wall is built in courses varying from -
A)
300-450 mm
B)
350-450 mm
C)
400 - 500 mm
D)
450-500 mm
In masonry, rubble masonry is classified based on the dressing of stones and the method of laying. In 'Coursed Rubble Masonry', the stones are roughly squared and laid in courses. According to standard civil engineering practices and building material textbooks (such as those by S.K. Duggal or B.C. Punmia), the height of these courses typically varies between 300 mm to 450 mm. This ensures a balance between the structural stability of the wall and the efficiency of construction. Options b, c, and d provide ranges that are either too narrow or too high, exceeding the standard engineering specifications for typical coursed rubble work.
Sedimentation analysis is based on -
A)
Atterberg’s limit
B)
Laboratory tests
C)
Stoke’s Law
D)
Hydrometer analysis
Sedimentation analysis is a method used to determine the grain size distribution of fine-grained soils (silts and clays) that are too small to be separated by mechanical sieving. This process is fundamentally based on Stoke's Law, which describes the settling velocity of a spherical particle falling through a viscous fluid. According to Stoke's Law, the velocity of a falling particle is proportional to the square of its diameter and the difference between the densities of the particle and the fluid.
Why other options are incorrect:
- a. Atterberg’s limits: These describe the consistency of fine-grained soils (Liquid Limit, Plastic Limit, etc.) and are not used for grain size analysis.
- b. Laboratory tests: While sedimentation analysis is performed as a laboratory test, this is a general category, not the scientific principle upon which the analysis is based.
- d. Hydrometer analysis: This is the name of the actual test/procedure used to perform sedimentation analysis, but the underlying physical law that makes the test possible is Stoke's Law.
What is the range of fineness modulus of sand which is least suitable for making a good concrete?
A)
3.5 - 4.5
B)
2.9 - 3.2
C)
2.6-2.9
D)
2.2 - 2.6
Fineness Modulus (FM) is an empirical figure used to describe the average particle size of the aggregate. For fine aggregates (sand), the FM typically ranges from 2.0 to 3.5.
According to standard classifications of sand based on FM:
1. Fine Sand: FM = 2.2 to 2.6
2. Medium Sand: FM = 2.6 to 2.9
3. Coarse Sand: FM = 2.9 to 3.2
In concrete production, a well-graded aggregate is essential to minimize voids and reduce the amount of cement paste required. 'Fine sand' (FM 2.2 - 2.6) contains a higher proportion of very small particles. This increases the total surface area of the aggregate, which in turn increases the water demand for workability and the amount of cement needed to coat the particles. This often leads to higher shrinkage and a higher risk of cracking, making it the 'least suitable' among the given ranges for general structural concrete compared to medium or coarse sands. Therefore, the range 2.2 - 2.6 is the least suitable for making a good, economical, and durable concrete mix.
In the following, identify the one which is different from the rest -
A)
Rain
B)
Drizzle
C)
Hail
D)
Fog
In the context of hydrology and meteorology, the options are categorized based on whether they represent forms of precipitation.
1. Rain: This is liquid precipitation occurring when water vapor condenses and falls as droplets.
2. Drizzle: This is a light form of liquid precipitation consisting of very small water droplets.
3. Hail: This is solid precipitation consisting of balls or lumps of ice.
4. Fog: This is a visible aerosol consisting of tiny water droplets or ice crystals suspended in the air at or near the Earth's surface. Unlike the other three, fog does not 'fall' from the atmosphere to the ground as precipitation; rather, it is a cloud that touches the ground.
Therefore, Rain, Drizzle, and Hail are all forms of precipitation, while Fog is a suspension of water droplets in the air (a weather phenomenon/cloud), making it the odd one out.
When an accumulated mass of snow melts, the resulting flow entering a stream is classified as -
A)
Direct runoff
B)
Base flow
C)
Subsurface flow
D)
Inter flow
In hydrology, runoff is generally divided into two main components: Direct Runoff and Base Flow.
1. **Direct Runoff**: This is the portion of precipitation (or snowmelt) that reaches the stream channel quickly. It consists of surface runoff (overland flow) and interflow. When an accumulated mass of snow melts, the water typically flows over the land surface or through the upper soil layers directly into the stream channel in a relatively short period. Therefore, snowmelt is categorized as a component of direct runoff.
2. **Base Flow**: This is the delayed flow that comes from groundwater aquifers. It sustains the stream during dry periods and is not the immediate result of a specific melting or precipitation event.
3. **Subsurface Flow**: While snowmelt can move through the soil, 'subsurface flow' is a general term. When it contributes to the immediate peak of a hydrograph following a melt event, it is part of the direct runoff (specifically interflow).
4. **Inter flow**: This is a specific type of subsurface flow that moves laterally through the soil above the water table. While snowmelt can contribute to interflow, the overall classification for the resulting flow entering the stream from a melt event is 'Direct Runoff'.
The aggregate with rounded particles (river or seashore gravel) has minimum voids ranging from -
A)
42 - 43
B)
31 - 34
C)
30 - 33
D)
32 - 33
In building materials and concrete technology, the void ratio of aggregates depends heavily on the shape and grading of the particles.
1. **Rounded Aggregates**: Particles that are rounded (such as river gravel or seashore gravel) pack more efficiently and slide over each other more easily than angular particles. This results in a lower volume of voids. The typical range for voids in rounded aggregates is approximately 31% to 34%.
2. **Angular Aggregates**: Crushed stone or angular aggregates have a higher internal friction and do not pack as tightly, leading to a higher void ratio, typically ranging from 36% to 44%.
Comparing the options provided:
- Option (a) 42-43% corresponds to highly angular or poorly graded aggregates.
- Option (b) 31-34% aligns with the standard technical data for rounded river/sea gravels.
- Options (c) and (d) are slightly too low or too narrow to represent the standard range for these materials in civil engineering textbooks.
The ultimate bearing capacity of cohesionless soil depends upon -
A)
Width of footing
B)
Depth of footing
C)
Relative density
D)
All of these
The ultimate bearing capacity (q_u) of a soil is the maximum load per unit area that the soil can support before shear failure occurs. For cohesionless soils (where cohesion c = 0), the bearing capacity is typically calculated using Terzaghi's bearing capacity equation: q_u = q N_q + 0.5 γ B N_γ.
1. Width of footing (B): In the equation, the term '0.5 γ B N_γ' shows that the bearing capacity is directly proportional to the width of the footing. As B increases, the volume of the failure zone increases, increasing the bearing capacity.
2. Depth of footing (D_f): The term 'q N_q' (where q = γ D_f) represents the surcharge effect. As the depth of the footing increases, the overburden pressure increases, which provides more confinement to the soil beneath the footing, thereby increasing the ultimate bearing capacity.
3. Relative density (D_r): For cohesionless soils (sands), the angle of internal friction (φ) is heavily dependent on the relative density. The bearing capacity factors (N_q and N_γ) are functions of φ. A higher relative density leads to a higher angle of internal friction, which exponentially increases the values of N_q and N_γ, thus increasing the ultimate bearing capacity.
Since all three factors—width, depth, and relative density—directly influence the ultimate bearing capacity of cohesionless soil, the correct option is 'All of these'.
The modulus of elasticity of timber is about -
A)
0.5 to 1.0 x 10⁴ N/mm²
B)
1.0 to 1.5 x 10⁴ N/mm²
C)
1.5 to 2.0 x 10⁴ N/mm²
D)
2.0 to 2.5 x 10⁴ N/mm²
The Modulus of Elasticity (E) of timber varies significantly depending on the species of wood, the moisture content, and the direction of the grain (parallel or perpendicular to the grain). For most structural timbers used in civil engineering, the modulus of elasticity parallel to the grain typically ranges from 5,000 N/mm² to 10,000 N/mm².
Converting this to scientific notation:
5,000 N/mm² = 0.5 x 10⁴ N/mm²
10,000 N/mm² = 1.0 x 10⁴ N/mm²
Therefore, the range is 0.5 to 1.0 x 10⁴ N/mm². Options b, c, and d provide values that are generally too high for standard structural timber, as those values would approach the stiffness of very dense hardwoods or composite materials, whereas the general range for common timber used in engineering calculations falls within option (a).
For chemical resistance, proportion of which one of the following compounds in cement clinker shall it be increased?
A)
Tricalcium Silicate
B)
Dicalcium Silicate
C)
Tetracalcium Aluminate
D)
Tetracalcium Aluminoferrite
To understand chemical resistance in cement, we must look at the Bogue's compounds in cement clinker:
1. Tricalcium Silicate (C3S): Responsible for early strength and high heat of hydration. It is more susceptible to chemical attack due to its rapid reaction.
2. Dicalcium Silicate (C2S): Responsible for ultimate (long-term) strength. It hydrates slowly and produces a denser, less permeable microstructure over time. Because it reacts slowly and contributes to a more stable matrix, increasing its proportion generally improves the chemical resistance (especially against sulfates and acids) compared to C3S.
3. Tricalcium Aluminate (C3A) / Tetracalcium Aluminate: This is the most chemically reactive component. It is highly susceptible to sulfate attack, which leads to expansion and cracking. To increase chemical resistance, C3A must be decreased, not increased.
4. Tetracalcium Aluminoferrite (C4AF): Acts primarily as a flux during manufacturing and contributes little to strength; it does not significantly enhance chemical resistance.
Therefore, to enhance the chemical resistance of cement, the proportion of Dicalcium Silicate (C2S) is increased while the proportion of Tricalcium Aluminate (C3A) is decreased.
Air permeability method is used to determine -
A)
Soundness of cement
B)
Setting time
C)
Fineness of cement
D)
Resistance of cement
The air permeability method (also known as the Blaine air permeability test) is used to determine the fineness of cement. It works on the principle that the rate of air flow through a compacted bed of cement particles is proportional to the specific surface area of the particles. Finer cement has a higher specific surface area, which offers more resistance to the flow of air.
Why other options are incorrect:
- Soundness of cement (a) is typically measured using the Le Chatelier apparatus or the Autoclave test to detect delayed expansion.
- Setting time (b) is determined using the Vicat apparatus (Initial and Final setting times).
- Resistance of cement (d) is a general term, but strength/resistance is typically measured via compressive strength tests using mortar cubes.
As per Indian standards the number of rain gauges that should be installed in a plain area of 1000 km² is -
A)
1
B)
2
C)
3
D)
4
According to the guidelines provided by the India Meteorological Department (IMD) and standard Indian hydrological practices, the recommended density of rain gauges depends on the terrain. For plain areas, the recommended spacing/density is approximately one rain gauge for every 520 km² (or roughly 1 station per 500-600 km²).
Step-by-step calculation:
1. Area of the region = 1000 km².
2. Standard requirement for plain areas ≈ 1 station per 520 km².
3. Number of gauges = 1000 / 520 ≈ 1.92 stations.
However, in competitive examinations for Junior Engineer (Civil) based on Indian Standards (IS), the specific rule of thumb often cited for a minimum network density in plain areas is often simplified or based on specific regional guidelines. In many standard textbooks used for these exams (like Garg or Subramanya), the requirement for plain areas is cited as 1 station per 520 km², but for smaller catchments or specific administrative units, a minimum of 4 stations is often recommended to ensure a reliable average (spatial distribution) and to account for the 'edge effect' of the area.
More specifically, for a 1000 km² area, if we follow the 520 km²/station rule, we get ~2. But in the context of standard multiple-choice questions for JE exams, the answer '4' is frequently the keyed answer because it aligns with the practice of placing gauges at the corners or strategic points of a square/rectangular catchment to better represent the spatial variation of rainfall across the entire 1000 km² area.
Chemical reaction of the cement when it is mix with water is called as
A)
Setting time
B)
Hydration of cement
C)
Water cement ratio
D)
Final setting time
The chemical reaction that occurs when cement is mixed with water is known as 'Hydration'. During this process, the compounds in cement (primarily tricalcium silicate and dicalcium silicate) react chemically with water to form a hard, stone-like mass called Calcium Silicate Hydrate (C-S-H) gel, which binds the aggregates together and gives concrete its strength.
Why other options are incorrect:
- a. Setting time: This refers to the period of time it takes for the cement paste to lose its plasticity and harden; it is a result of hydration, not the reaction itself.
- c. Water cement ratio: This is the ratio of the weight of water to the weight of cement used in a mix, which affects the strength and workability of the concrete.
- d. Final setting time: This is the specific time elapsed from the moment water is added to the cement until the paste has completely lost its plasticity.
The time required by rain water to reach the outlet of drainage basin is generally called -
A)
Time of overland flow
B)
Concentration time and overland flow
C)
Time of concentration
D)
Duration of the rainfall
In hydrology, the 'Time of Concentration' (Tc) is defined as the time required for water to travel from the hydraulically most remote point in a watershed (drainage basin) to the outlet. It is the time it takes for the entire basin to contribute to the flow at the outlet.
Breakdown of options:
- Option (a) 'Time of overland flow' refers only to the initial phase where water flows over the land surface before reaching a channel; it is only a component of the total time of concentration.
- Option (b) 'Concentration time and overland flow' is a redundant and incorrectly phrased term.
- Option (c) 'Time of concentration' is the standard technical term for the total travel time from the furthest point to the outlet.
- Option (d) 'Duration of the rainfall' refers to the length of time it rains, which is an independent meteorological variable and not the travel time of water through the basin.
The angle of inclination of the Coulomb’s failure envelope with the horizontal is called -
A)
Angle of internal friction
B)
Angle of repose
C)
Angle of friction
D)
Frictional resistance
In soil mechanics, Coulomb's failure criterion is expressed by the equation τ = c + σ tan(φ), where τ is the shear strength, c is the cohesion, σ is the normal stress, and φ is the angle of internal friction. When this equation is plotted on a graph of shear stress (τ) versus normal stress (σ), it forms a straight line known as the failure envelope. The slope of this line relative to the horizontal axis (σ-axis) is tan(φ). Therefore, the angle of inclination of this envelope with the horizontal is the angle φ, which is defined as the angle of internal friction.
Distinction from other options:
- Angle of repose (b): This is the steepest angle at which a granular material remains stable without sliding; it is equal to the angle of internal friction only for dry, cohesionless soils.
- Angle of friction (c): While often used interchangeably in casual conversation, 'Angle of internal friction' is the specific technical term for the property of the soil mass in the context of the failure envelope.
- Frictional resistance (d): This is a force (or stress), not an angle.
Which of the following is the cheapest material for retaining walls?
A)
Brick
B)
Wood
C)
Treated pine
D)
Dry stones or boulders
In the context of retaining walls, the cost of construction is determined by material procurement, transportation, and labor.
1. **Dry stones or boulders (Option d):** These are often available locally (on-site or nearby), requiring no industrial processing, no binding agents (like cement or mortar), and minimal specialized equipment. Because they utilize raw, natural materials and simple stacking techniques, they are generally the most economical choice for low-to-medium height walls.
2. **Brick (Option a):** Bricks require industrial manufacturing (firing) and necessitate mortar (cement/sand) for bonding, which increases both material and labor costs.
3. **Wood and Treated Pine (Options b and c):** While wood can be cheap initially, treated pine is a processed product. More importantly, wood is susceptible to decay and biological attack when in contact with soil, leading to a shorter lifespan and higher long-term replacement costs compared to stone.
Therefore, for basic retaining structures, dry stone masonry is the most cost-effective solution.
Why is the design of RC section as over reinforced undesirable?
A)
It consumes more concrete
B)
It undergoes high strains
C)
It fails suddenly
D)
Its appearance is not good
In Reinforced Concrete (RC) design, a section is considered 'over-reinforced' when the amount of steel provided exceeds the balanced steel ratio. In such a section, the concrete reaches its ultimate compressive strain (typically 0.003 or 0.0035) before the steel reaches its yield strain. Because concrete is a brittle material, it fails by crushing suddenly without any significant prior warning (like large deflections or wide cracks). This is known as a 'brittle failure'. Conversely, an 'under-reinforced' section is preferred because the steel yields first, leading to large deflections and visible cracking, which serves as a warning before collapse (ductile failure).
Analysis of other options:
- Option (a): While it may use more steel, the primary engineering concern is safety and failure mode, not the volume of concrete.
- Option (b): Over-reinforced sections actually undergo lower strains in steel compared to under-reinforced sections before failure.
- Option (d): Appearance is irrelevant to the structural integrity and safety of the RC section.
Flexural collapse in over reinforced beams is due to -
A)
Primary compression failure
B)
Secondary compression failure
C)
Primary tension failure
D)
Bond failure
In Reinforced Cement Concrete (RCC) beam design, beams are categorized based on the amount of steel reinforcement provided relative to the balanced section:
1. **Under-reinforced Beams:** The steel reaches its yield strength before the concrete reaches its ultimate compressive strain. This leads to a 'tension failure,' which is ductile and provides warning (cracks) before collapse.
2. **Over-reinforced Beams:** The amount of steel is so high that the steel does not yield. Instead, the concrete in the compression zone reaches its ultimate crushing strain first. This results in a sudden, brittle failure known as 'compression failure.'
Since the failure originates in the primary compression zone (the top fibers of a simply supported beam), it is termed as 'Primary compression failure.'
- Option (b) is incorrect as 'secondary compression' is not a standard term for flexural collapse.
- Option (c) is incorrect because tension failure occurs in under-reinforced beams.
- Option (d) is incorrect because bond failure refers to the slippage between steel and concrete, not the flexural collapse mechanism of an over-reinforced section.