Difficulty: Easy
Correct Answer: All of the above
Explanation:
Introduction / Context:
Moisture content strongly influences the engineering response of soils. From earthworks to slope stability and granular stockpiles, the water content governs lubrication between particles, capillary suction, and the ease with which a soil can be compacted. Recognizing the direction and magnitude of these effects is fundamental in field control and design.
Given Data / Assumptions:
Concept / Approach:
Angle of repose: For dry to slightly moist sands, small amounts of moisture can increase apparent cohesion via capillary tension, often increasing the stable angle. With excess water, lubrication dominates and the angle may reduce. Compaction: Proctor relationships show an optimum moisture content where maximum dry density is achieved; water content determines required compactive effort and achievable density. Cohesion: In clays, water content around the plastic range controls undrained shear strength; increasing water content generally reduces undrained strength. In sands, capillarity at low moisture can induce apparent cohesion that disappears when saturated.
Step-by-Step Solution:
Verification / Alternative check:
Laboratory Proctor tests, vane shear in clays at varying water contents, and angle-of-repose demonstrations with dry vs. damp sand corroborate these trends.
Why Other Options Are Wrong:
Each individual effect is real; selecting only one would ignore the coupled nature of moisture effects. Thus 'All of the above' is the comprehensive choice.
Common Pitfalls:
Assuming monotonic trends for angle of repose with water; ignoring that optimal compaction depends on soil type and gradation.
Final Answer:
All of the above
Discussion & Comments