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Examoogle • User • info@examoogle.com • EE-2024-8821
Chapter 1 of 12 • Page 1 of 248🔒 Protected PDF • Watermarked
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With increase in water content, soil suction
decreases
remains same
increases
all the above
decreases
Soil suction is defined as the negative pressure in the soil pore water relative to the ambient atmospheric pressure. As the water content of the soil increases, the pore spaces fill with water, reducing the capillary tension and matrix forces, which leads to a decrease in suction.
Soil suction is defined as the negative pressure in the soil pore water relative to the ambient atmospheric pressure. As the water content of the soil increases, the pore spaces fill with water, reducing the capillary tension and matrix forces, which leads to a decrease in suction.
ψ=ua−uw — where ψ is matric suction, ua is pore air pressure, and uw is pore water pressure.
ψ∝w1 — conceptual representation showing suction is inversely related to water content w.
Soil suction comprises matric suction and osmotic suction. Matric suction arises primarily due to capillary action within the soil voids; as water content increases, the menisci between soil particles become flatter or disappear, reducing the capillary potential. Consequently, the suction force decreases as the soil moves toward saturation.
Soil suction is a measure of the soil's affinity for water.
Suction is highest in dry soils and approaches zero at full saturation.
The Soil-Water Characteristic Curve (SWCC) describes the relationship between suction and volumetric water content.
Matric suction dominates in unsaturated soil mechanics.
Predicts soil volume change behavior (swelling/shrinkage).
Essential for stability analysis of unsaturated slopes.
Measurement is complex and sensitive to initial conditions.
High dependency on soil structure and mineralogy.
Geotechnical design for expansive soils.
Agricultural irrigation management.
Hydrological modeling of vadose zones.
At 100% saturation, matric suction is zero.
Option B (remains same) is incorrect as suction is a dynamic property dependent on state.
Option C (increases) is the inverse of the actual physical behavior.
A is correct — Soil suction decreases as water content increases because the capillary forces (meniscus effects) diminish with the saturation of pore spaces.
Always remember that suction and water content have an inverse relationship; this is the fundamental principle behind the Soil-Water Characteristic Curve (SWCC).