Correct Answer: Clay
Explanation: The angle of internal friction is generally lower for cohesive soils like clay. Clay particles have a plate-like structure, and their ability to interlock results in lower internal friction compared to granular soils.
Correct Answer: H/2
Explanation: In a soil layer with double drainage, the drainage path is equal to half the thickness of the soil layer (H/2). This configuration allows drainage from both the top and bottom of the layer.
Correct Answer: Layered soils
Explanation: Westergaard’s theory is commonly used for the analysis of layered soils. It provides solutions for stress distribution in layered systems.
Correct Answer: The water chemically combined in the crystal structure of the soil material
Explanation: Absorbed water in soil refers to the water that is chemically combined within the crystal structure of the soil particles. It is not free to move through the soil by gravity.
Correct Answer: All of the above
Explanation: The angle of internal friction is influenced by various factors, including particle shape and roughness, normal direct pressure, and the amount of interlocking between soil particles.
Correct Answer: 30cm & 20cm
Explanation: The penetration number is determined by the number of blows required to penetrate the sampler and cone to a specified depth, such as 30cm & 20cm. It is a measure of the resistance of the soil to penetration.
Correct Answer: Below GL
Explanation: An isobar is a line connecting points below the groundwater level (GL) that have equal total stress. It helps visualize stress distribution in soil beneath the ground surface.
Correct Answer: Onion
Explanation: The shape and structure of an isobar are often likened to that of an onion. It represents lines of equal stress below the groundwater table in the soil.
Correct Answer: Soft chalk
Explanation: Soft chalk is typically a weak and compressible soil, leading to a lower safe load compared to the other mentioned soils. Safe load capacity is influenced by the strength and compressibility of the soil.
Correct Answer: The retaining wall tends to move away from the backfill
Explanation: Active earth pressure is the lateral pressure exerted by the soil when the retaining wall tends to move away from the backfill. It is a critical consideration in the design of retaining structures.
Correct Answer: Active earth pressure
Explanation: When the lateral earth pressure moves towards the retaining wall, it indicates active earth pressure. This occurs when the wall tends to move away from the backfill.
Correct Answer: Always less than passive earth pressure
Explanation: Active earth pressure is generally less than passive earth pressure. It occurs when the retaining wall tends to move away from the backfill.
Correct Answer: Retaining wall tends to move towards the backfill
Explanation: Passive earth pressure occurs when the retaining wall tends to move towards the backfill.
Correct Answer: Square of the depth of the soil
Explanation: The total lateral earth pressure is proportional to the square of the depth of the soil. This relationship is part of the equations used to calculate lateral earth pressure.
Correct Answer: Move into the soil
Explanation: Passive earth pressure occurs when the retaining wall tends to move into the soil. It is the lateral pressure exerted by the soil in this condition.
Correct Answer: No movement relative to the backfill
Explanation: Earth pressure at rest occurs when the retaining wall has no movement relative to the backfill. It represents the lateral pressure exerted under this condition.
Correct Answer: tan2 (45°-Φ/2)
Explanation: The active earth pressure is proportional to tan2 (45°-Φ/2), where Φ is the angle of internal friction of the soil.
Correct Answer: tan2 (45°+Φ/2)
Explanation: The passive earth pressure is proportional to tan2 (45°+Φ/2), where Φ is the angle of internal friction of the soil.
Correct Answer: μ / (1-μ)
Explanation: The earth pressure at rest is proportional to μ / (1-μ), where μ is Poisson’s ratio, and Φ is the angle of internal friction of the soil.
Correct Answer: Greater than active earth pressure but lesser than passive earth pressure
Explanation: The coefficient of earth pressure at rest is greater than the active earth pressure but lesser than the passive earth pressure. It represents the lateral pressure when the wall has no movement relative to the backfill.
Correct Answer: 1-sin Φ / 1+sin Φ
Explanation: The coefficient of the active earth pressure (Ka) is given by (1 – sin Φ) / (1 + sin Φ).
Correct Answer: All of the above
Explanation: Rankine’s theory assumes that the soil is semi-finite, homogeneous, dry, and cohesionless, the ground surface is a plane (inclined or horizontal), and the back of the wall is vertical and smooth.
Correct Answer: Hc = γh2/2 tan2(45°-Φ)
Explanation: The active earth pressure (Hc) is given by γh2/2 tan2(45°-Φ), where γ is the unit weight of the soil and Φ is the angle of internal friction.
Correct Answer: Hc = {μγ/2(1-μ)}h2
Explanation: The earth pressure at rest (Hc) is given by {μγ/2(1-μ)}h2
Correct Answer: Hc = γh2/2 tan2(45°+Φ)
Explanation: The passive earth pressure (Hc) is proportional to γh2/2 tan2(45°+Φ), where γ is the unit weight of the soil and Φ is the angle of internal friction.
Correct Answer: Hc = 4c/γ tan(45°+Φ)
Explanation: The critical vertical depth H of free-standing soil can be up to Hc = 4c/γ tan(45°+Φ), where c is the cohesion and γ is the unit weight of the soil.
Correct Answer: Ka-Ko-Kp
Explanation: The correct sequence regarding different coefficients of friction in increasing order is Ka (active)-Ko (at rest)-Kp (passive).
Correct Answer: 3
Explanation: The coefficient of active earth pressure (Ka) is reciprocal to the coefficient of passive earth pressure (Kp). Therefore, if Kp is 1/3, then Ka is 3.
Correct Answer: B/6
Explanation: The maximum permissible eccentricity for a retaining wall not to fail in tension is B/6.
Correct Answer: H/3 above the base parallel to the sloping surface
Explanation: In the case of a backfill with a sloping surface, the total active pressure on the wall of height H acts at H/3 above the base parallel to the sloping surface.
Correct Answer: More earth pressure
Explanation: Submerged backfill exerts more earth pressure compared to dry backfill.
Correct Answer: To find the thickness of a flexible pavement
Explanation: The California Bearing Ratio (CBR) test is used to find the thickness of a flexible pavement.
Correct Answer: Surcharge
Explanation: The position of the backfill above a horizontal plane at the elevation of the top of the structure is known as surcharge.
Correct Answer: q times the lateral pressure within the surface
Explanation: The lateral pressure exerted by a uniform surcharge is q times the lateral pressure within the surface.
Correct Answer: h/3 from the base of the wall
Explanation: The earth pressure acting at a height of h/3 in the case of an inclined surcharge.
Correct Answer: Wall face is smooth and vertical
Explanation: Rankine’s earth pressure theory assumes that the wall face is smooth and vertical.
Correct Answer: All of the above
Explanation: The assumption of Rankine’s theory includes the soil being semi-finite, homogeneous, dry, and cohesionless, the ground surface being a plane (inclined or horizontal), and the back of the wall being vertical and smooth.
Correct Answer: Hydrostatic
Explanation: The distribution of earth pressure with depth is hydrostatic.
Correct Answer: Coulomb
Explanation: The assumption of wedge-shaped failure is made by Coulomb.
Correct Answer: Sliding
Explanation: If the resultant force at the face of the retaining wall is much more than frictional resistances at the bottom, the failure will be due to sliding.
Correct Answer: Crushing
Explanation: If the resultant force at the bottom of the retaining wall lies outside the middle third, the failure will be due to crushing.
Correct Answer: Extra load on the horizontal backfill
Explanation: In the case of retaining walls, surcharge refers to the extra load on the horizontal backfill.
Correct Answer: 4c/γ
Explanation: In cohesive soils, the depth of the vertical cut up to which no lateral support is required is given by 4c/γ.
Correct Answer: Culmann’s method
Explanation: One of the graphical methods for earth pressure determination is Culmann’s method.
Correct Answer: Retaining walls for waterfront construction
Explanation: Sheet pile walls are used as retaining walls for waterfront construction.
Correct Answer: Tie rods which are anchored
Explanation: Sheet piles are held in position by tie rods that are anchored.
Correct Answer: Active and passive earth pressure both considered
Explanation: For the design of sheet pile walls, both active and passive earth pressure are considered as they are embedded in soil.
Correct Answer: Depends on the size of the footing
Explanation: The bearing capacity of soil primarily depends on the size of the footing.
Correct Answer: Replacement of black cotton soil by sand
Explanation: The most suitable method for increasing the bearing capacity of black cotton soil is the replacement of black cotton soil by sand.
Correct Answer: Swelling and shrinkage nature
Explanation: Black cotton soil is not suitable for foundations due to its swelling and shrinkage nature.
Correct Answer: Water content
Explanation: The bearing capacity of soil is significantly influenced by its water content. Changes in water content can alter soil properties, affecting its strength and load-bearing capacity.
Correct Answer: Grain size of the soil
Explanation: The bearing capacity of soil is closely related to the grain size of the soil particles. The arrangement and size of particles affect the overall strength and load-bearing ability of the soil.
Correct Answer: All of the above
Explanation: Various methods, such as increasing foundation depth, soil compaction, and replacing weak soil with stronger materials, can enhance the bearing capacity of weak soils. Combining these methods may provide effective improvement.
Correct Answer: Poor for backfills because of large lateral pressure
Explanation: Cohesive soils, while having high shear strength, can generate significant lateral pressure, making them less suitable for backfills where excessive pressure can impact retaining structures.
Correct Answer: Is more in well-compacted clays
Explanation: Cohesion, representing the internal molecular attraction of soil particles, tends to be higher in well-compacted clays, contributing to the soil’s overall strength.
Correct Answer: All of the above
Explanation: The bearing capacity of soil depends on various factors, including the size and shape of particles as well as cohesive properties. All these factors collectively influence the soil’s ability to bear loads.
Correct Answer: Both (a) and (b) of above
Explanation: Bearing capacity is determined through tests like the plate load test and the standard cone test. These tests help assess the soil’s strength and load-bearing characteristics.
Correct Answer: Moist clay
Explanation: Moist clay, especially when saturated, often exhibits the minimum or least bearing capacity among various soil types due to its compressible nature and sensitivity to moisture content changes.
Correct Answer: Load intensity beyond which the soil should not be loaded
Explanation: The safe bearing capacity represents the maximum load intensity that a soil can safely support without undergoing excessive settlement or failure. It is the limit beyond which loading should not proceed to ensure stability.
Correct Answer: Load at which the soil fails
Explanation: The ultimate bearing capacity is the maximum load that a soil can withstand before failure occurs. It represents the point at which the soil structure collapses or undergoes excessive deformation.
Correct Answer: q = cNc + γDf Nq + 0.5γB.Ny
Explanation: Not available
Correct Answer: q = 0.67cN‘c + γDf Nq + 0.5γB.N‘y
Explanation: Not available
Correct Answer: q = 1.2cNc + γDf Nq + 0.4γB.Ny
Explanation: Not available
Correct Answer: Angle of internal friction
Explanation: The bearing capacity factors are functions of the angle of internal friction and are crucial parameters in determining the bearing capacity of soil.
Correct Answer: All of the above
Explanation: Terzaghi’s analysis makes assumptions including homogeneous and isotropic soil, well-defined elastic and plastic zones, and failure zones not extending above the horizontal plane through the base of the footing.
Correct Answer: 5.14c
Explanation: Terzaghi’s theory provides an expression for the ultimate bearing capacity at the ground surface, and for purely cohesive soils with a smooth base, it is given by 5.14c.
Correct Answer: 4.5c to 6c
Explanation: The ultimate bearing capacity for frictionless soils typically falls in the range of 4.5c to 6c, where c is the cohesion of the soil.
Correct Answer: Cohesion and effective angle of shearing resistance
Explanation: The rise of the water table impacts soil cohesion and the effective angle of shearing resistance, both of which are critical in determining the bearing capacity.
Correct Answer: 50%
Explanation: The rise of the water table in cohesionless soils up to the ground surface can lead to a reduction of approximately 50% in the net ultimate bearing capacity.
Correct Answer: 1.00
Explanation: When the water table is at a depth equal to the width of the footing below the footing, there is no reduction in the bearing capacity, and the reduction factor is 1.00.
Correct Answer: 0.75
Explanation: The reduction factor for the water table at a depth equal to half of the width of the footing is 0.75, indicating a reduction in bearing capacity due to the influence of the water table.
Correct Answer: 0.50
Explanation: The reduction factor for the water table just below the footing is 0.50, indicating a significant reduction in bearing capacity due to the proximity of the water table.
Correct Answer: Increases and then decreases bearing capacity
Explanation: Initially, raising the water table increases bearing capacity, but there is a point beyond which further rise decreases bearing capacity due to excessive pore water pressure.
Correct Answer: Safe bearing capacity
Explanation: The safe bearing capacity is the maximum pressure a soil can withstand without shear failure, ensuring a factor of safety against failure.
Correct Answer: Net bearing capacity
Explanation: Net bearing capacity is the minimum net pressure intensity causing shear failure of the soil, considering both cohesion and friction.
Correct Answer: Fill settles relative to the pile
Explanation: Negative skin friction occurs when the fill settles relative to the pile, causing additional downward load on the pile.
Correct Answer: Decreases the load-carrying capacity of the pile
Explanation: Negative skin friction reduces the effective load-carrying capacity of the pile by introducing additional downward forces.
Correct Answer: Sands
Explanation: Skin friction is typically higher in sands compared to other soil types, contributing significantly to the load-carrying capacity of piles.
Correct Answer: Increases
Explanation: Skin friction contributes to the load-carrying capacity of the pile, increasing its overall capacity to resist vertical loads.
Correct Answer: Both allowable settlement & ultimate bearing capacity of soil
Explanation: The allowable bearing pressure for a foundation is influenced by both the allowable settlement criteria and the ultimate bearing capacity of the soil, ensuring a balance between safety and serviceability.
Correct Answer: Skin friction & point bearing
Explanation: Well foundations in sandy soils derive their bearing capacity from both skin friction along the shaft and point bearing at the base of the well.
Correct Answer: To transfer load from the steining to the soil
Explanation: The bottom plug in a well foundation is used to transfer the load from the steining (the vertical shaft of the well) to the underlying soil.
Correct Answer: Filled with sand and consolidated on
Explanation: The well in a well foundation is typically filled with sand, and consolidation is done to ensure stability and load transfer to the underlying soil.
Correct Answer: All of the above
Explanation: The minimum depth of a building foundation depends on the type of soil. For sandy soils, it is typically 80 cm to 100 cm, for clay soils 90 cm to 160 cm, and for rocky soils 5 cm to 50 cm.
Correct Answer: Structures on river beds
Explanation: Well foundations are commonly used under structures located on river beds, where the load-bearing capacity of the soil is improved by the well structure.
Correct Answer: d = √ [(3W/4fl)(L-1)]
Explanation: The minimum depth of a footing carrying a heavy load is given by the provided formula, which considers the total load, friction factor, and the length of the footing.
Correct Answer: q/γ (1-sinθ/1+sinθ)2
Explanation: According to Rankine’s analysis, the minimum depth of the foundation is given by the provided formula, considering the applied load, soil density, and the angle of internal friction.
Correct Answer: Shallow foundation
Explanation: A raft foundation is a type of shallow foundation that spreads the load over a large area, preventing excessive settlement.
Correct Answer: Depth is less than its width
Explanation: A foundation is classified as shallow if its depth is less than its width. This indicates that the foundation relies on the bearing capacity of the near-surface soils.
Correct Answer: Depth to width ratio is more than 2
Explanation: A foundation is classified as deep if the depth to width ratio exceeds a certain threshold, indicating that the foundation extends deep into the soil to achieve the required bearing capacity.
Correct Answer: Length to width ratio is between 1 and 2
Explanation: A spread foundation is classified based on the length to width ratio, and it is considered spread when this ratio is between 1 and 2.
Correct Answer: Length to width ratio is more than 2
Explanation: A continuous foundation is classified based on the length to width ratio, and it is considered continuous when this ratio is more than 2.
Correct Answer: Length is very large compared with uniform width
Explanation: A strip foundation is characterized by its length being very large compared to its width, distributing the load over a strip of soil.
Correct Answer: Number of columns are two and are spaced close to each other
Explanation: Combined footings are used when there are two columns and they are spaced close to each other, requiring a combined foundation.
Correct Answer: Heavy loaded situations
Explanation: A grillage foundation, which consists of closely spaced beams and joists, is used under heavy loaded situations to distribute the load.
Correct Answer: When required bearing area is not available
Explanation: Pile foundations are used when the required bearing area is not available at the shallow depth, and they are suitable for various soil conditions.
Correct Answer: Tall buildings
Explanation: Pile foundations are commonly used in tall buildings to transfer the loads to deeper, more stable soil layers.
Correct Answer: 2
Explanation: A minimum of two piles is needed to support a wall to provide stability and prevent rotation.
Correct Answer: 3
Explanation: A minimum of three piles is needed to support a column, providing stability and preventing translation and rotation.
Correct Answer: Decreases
Explanation: Negative skin friction, caused by downward movement of soil, tends to reduce the load-carrying capacity of the pile by creating additional downward forces.
FAQs on Soil Mechanics MCQs for Civil Engineers
▸ What is soil mechanics in civil engineering?
Soil mechanics is a branch of civil engineering that deals with the behavior of soil and its applications in construction. It involves studying the physical properties of soil, its classification, and the principles of stress, strain, and shear strength. For more detailed MCQs on soil mechanics, visit gkaim.com.
▸ How can I prepare for Soil Mechanics MCQs for civil engineering exams?
To prepare for Soil Mechanics MCQs, you should focus on understanding key concepts such as soil properties, compaction, consolidation, and slope stability. Practicing a variety of MCQs and reviewing detailed solutions will also be beneficial. Explore comprehensive MCQs on this topic at gkaim.com.
▸ What are the fundamental concepts covered in Soil Mechanics MCQs?
Fundamental concepts covered in Soil Mechanics MCQs include soil classification, compaction, permeability, consolidation, shear strength, and earth pressure theories. Each of these topics is crucial for designing stable foundations and structures. Visit gkaim.com for detailed MCQs and explanations.
▸ Where can I find reliable MCQs on Soil Mechanics?
Reliable MCQs on Soil Mechanics can be found on educational websites like gkaim.com. These sites offer a variety of questions with detailed explanations to help you understand the concepts thoroughly and prepare for exams effectively.
▸ What are the types of soil tests commonly included in Soil Mechanics MCQs?
Common soil tests included in Soil Mechanics MCQs are Atterberg limits, Proctor compaction test, permeability test, triaxial shear test, and consolidation test. Understanding these tests and their applications is essential for civil engineers. Detailed MCQs on these tests are available at gkaim.com.
▸ How does soil compaction affect construction projects?
Soil compaction increases the density of soil, which improves its load-bearing capacity and reduces settlement issues. Properly compacted soil ensures the stability and longevity of structures. For MCQs related to soil compaction and its impact, visit gkaim.com.
▸ Why is understanding soil permeability important for civil engineers?
Understanding soil permeability is crucial for designing effective drainage systems and ensuring the stability of structures. Permeability determines how easily water can flow through soil, affecting foundation design and soil stability. Find more about soil permeability in the MCQs at gkaim.com.
▸ What is the significance of shear strength in soil mechanics?
Shear strength is a critical property of soil that determines its ability to resist sliding or failure under load. It is essential for designing stable foundations and slopes. Detailed MCQs on shear strength and its significance can be found at gkaim.com.
▸ How do consolidation and settlement affect building foundations?
Consolidation and settlement affect building foundations by causing gradual deformation under load. Understanding these processes helps in designing foundations that minimize settlement and ensure structural stability. Explore MCQs on consolidation and settlement at gkaim.com.
▸ What are the applications of soil mechanics in civil engineering projects?
Applications of soil mechanics in civil engineering include foundation design, slope stability analysis, earth retaining structures, and pavement design. It helps in predicting and improving the performance of these structures. Visit gkaim.com for detailed MCQs on the applications of soil mechanics.