Which soil classification is based on the particle size distribution?
A Atterberg limits
B Unified Soil Classification System
C AASHTO
D Shear strength
The Unified Soil Classification System (USCS) classifies soils based on their particle size distribution and their behavior. It uses symbols to categorize soils into groups like gravel, sand, silt, and clay for easier analysis in engineering applications.
What is the effect of compaction on soil permeability?
A No effect
B Depends on water content
C Decreases permeability
D Increases permeability
Compaction decreases soil permeability by reducing the voids between particles. This leads to a denser soil structure, which limits the flow of water and other fluids, especially in finer soils like clay.
Which of the following methods is used to improve soil shear strength?
A Adding chemicals
B Reducing compaction
C Increasing moisture content
D Drying the soil
Chemical stabilization methods, such as adding lime or cement, are commonly used to enhance the shear strength of soil. These chemicals bind soil particles together, improving their resistance to deformation and failure.
What does consolidation of soil involve?
A Increase in volume
B Decrease in volume
C No change in volume
D Increase in water content
Consolidation is the process by which a saturated soil decreases in volume over time due to the expulsion of pore water. This is particularly important in clay soils, which have low permeability and slow consolidation rates.
What is the primary objective of soil sampling?
A To obtain a representative soil sample for analysis
B To calculate bearing capacity
C To measure soil compaction
D To measure soil permeability
Soil sampling is done to collect a sample that accurately represents the soil in a given area. This sample is analyzed for various properties like texture, strength, and permeability to guide construction and design.
Which of the following tests determines the liquid limit of soil?
A Triaxial test
B Proctor test
C Atterberg limits test
D CBR test
The Atterberg limits test measures the liquid limit, plastic limit, and shrinkage limit of soils, primarily clay. It helps classify the soil’s consistency and behavior at various moisture contents, crucial for understanding its workability.
The term “capillary rise” in soils refers to:
A Water flowing downward
B Soil drying out
C Water flowing downward
D Water movement against gravity
Capillary rise refers to the movement of water upward through small pores in the soil, against gravity. This occurs due to surface tension between water molecules and the soil particles, particularly in fine-grained soils like clays.
Which soil type has the highest plasticity?
A Silt
B Clay
C Gravel
D Sand
Clay has the highest plasticity among soil types. Its small particles allow it to retain water and maintain its shape when molded, making it more plastic than other soil types like sand or gravel, which are less cohesive.
What is a common method to test the shear strength of a soil sample?
A Direct shear test
B CBR test
C Plate load test
D Proctor test
The direct shear test is commonly used to measure the shear strength of soils. It involves applying a shear force to a soil sample, then determining the soil’s resistance to shear failure, providing insight into its strength under stress.
What does “soil compaction” achieve?
A Increases soil strength
B Increases permeability
C Reduces soil volume
D Decreases permeability
Soil compaction reduces the voids between particles, which leads to a reduction in soil volume. This results in higher density and strength, improving the soil’s ability to support loads, crucial for foundation stability in construction.
Which of the following affects the rate of soil consolidation?
A Applied load
B Soil texture
C Water content
D All of the above
The rate of consolidation is influenced by factors like soil texture (permeability), water content, and applied load. Fine-grained soils like clay consolidate more slowly than coarse-grained soils like sand, as they have lower permeability.
What is the purpose of the California Bearing Ratio (CBR) test?
A To measure the strength of subgrade soils for road design
B To assess soil plasticity
C To determine soil compaction
D To measure soil permeability
The CBR test evaluates the strength of subgrade soils by comparing their resistance to penetration under a standard load. It is used primarily in road construction to assess soil suitability for supporting traffic loads.
Which property of soil is determined by the Proctor test?
A Liquid limit
B Optimum moisture content for compaction
C Shear strength
D Plasticity
The Proctor test determines the optimum moisture content at which a soil type achieves maximum dry density when compacted. This is crucial for ensuring effective compaction in construction, leading to stable foundations and structures.
What happens to soil’s shear strength as the moisture content increases?
A Shear strength increases
B Shear strength doubles
C Shear strength decreases
D Shear strength remains unchanged
As the moisture content increases in soil, the shear strength generally decreases. Water acts as a lubricant between soil particles, reducing friction and making the soil more prone to sliding or failure under stress.
Which of the following tests helps in determining the compaction characteristics of soil?
A CBR test
B Proctor test
C Triaxial test
D Proctor test
The Proctor test is used to determine the compaction characteristics of soil by identifying the moisture content that leads to maximum dry density. This helps engineers achieve optimal compaction for foundation stability and soil strength.