Soil-Water Characteristic Curve (SWCC) ppt

geo

1. Understanding the Soil Water Characteristic Curve (SWCC) An Academic Presentation

2. Introduction to SWCC • The Soil Water Characteristic Curve (SWCC) describes the relationship between soil water content and suction. • SWCC is essential in understanding unsaturated soil behavior, water retention, and permeability. • Applications: Widely used in geotechnical, agricultural, and environmental engineering.

3. Theoretical Background • Water Retention in Soil: Phases of soil (solid, liquid, gas) and concept of suction. • Suction: Total, matric, and osmotic suction—role in unsaturated soils. • Types of Water in Soil: Gravitational, capillary, and hygroscopic water.

4. Components of SWCC • Suction (x-axis): Typically measured in kPa. • Water Content (y-axis): Volumetric/gravimetric water content or degree of saturation. • Key regions: Air-entry value, residual water content, and desaturation zone.

5. Measurement Techniques • Laboratory Methods: Pressure plate extractor, Tempe cell, Dew-point potentiometer. • Field Methods: Tensiometers, Time domain reflectometry (TDR), Electrical resistivity. • Pros and cons of different methods.

6. SWCC Shapes and Soil Types • Influence of soil texture: - Clay soils: High water retention, slow desaturation. - Sandy soils: Low water retention, rapid desaturation. - Loam: Moderate water retention.

7. Air-Entry Value (AEV) • The suction at which air begins to enter soil pores. • Important for defining soil behavior during drying/wetting cycles. • Impact on hydraulic conductivity.

8. Factors Affecting SWCC • Soil Structure: Aggregated vs. non-aggregated. • Soil Density: Influence of compaction on SWCC. • Temperature and Salinity: Effect of environmental conditions. • Hysteresis: Differences between drying and wetting curves.

9. Application in Geotechnical Engineering • SWCC in slope stability, landfill design, and foundation engineering. • Predicting settlement, heave, and unsaturated soil behavior.

10. Application in Agriculture and Hydrology • SWCC in irrigation management and predicting plant available water. • Use in drainage design and water conservation.