CELE Geotechnical Engineering — Soil Properties and Phase RelationshipsConcept Map

Concept

Phase Diagram and Volume Relationships

Sub Concepts

• Total volume (V)
• Solid volume (Vs)
• Void volume (Vv)
• Water volume (Vw)
• Air volume (Va)

Relationship To Central

Foundation for understanding soil composition and void structure

Concept

Phase Ratios (Dimensionless Quantities)

Sub Concepts

• Void ratio (e = Vv/Vs)
• Porosity (n = Vv/V)
• Water content (w = Ww/Ws)
• Degree of saturation (S = Vw/Vv)
• Specific gravity of solids (Gs)

Relationship To Central

Quantifies proportions of soil phases

Concept

Master Identity and Relationships

Sub Concepts

• Se = wGs (master identity)
• e and n conversion formulas
• Application in saturation calculations

Relationship To Central

Interlinks all phase ratios through a governing equation

Concept

Unit Weights (Weight-Volume Relationships)

Sub Concepts

• Dry unit weight (γdry)
• Moist/bulk unit weight (γ)
• Saturated unit weight (γsat)
• Submerged/effective unit weight (γ')
• Water unit weight (γw ≈ 9.81 kN/m³)

Relationship To Central

Defines density-like properties for design calculations

Concept

Soil Classification Based on Saturation State

Sub Concepts

• Dry soil (S = 0)
• Partially saturated soil (0 < S < 1)
• Saturated soil (S = 1)

Relationship To Central

Categorizes soil conditions affecting engineering behavior

Concept

Calculation Procedures and Problem-Solving

Sub Concepts

• Finding e from n and vice versa
• Determining w from saturation data
• Computing unit weights from phase ratios
• Back-calculating degree of saturation

Relationship To Central

Practical application of phase relationships in geotechnical design

To

Void Ratio (e = Vv/Vs)

From

Phase Diagram (V, Vs, Vv, Vw, Va)

Strength

strong

Relationship

Void ratio is calculated directly from volumes in the phase diagram

To

Porosity (n = Vv/V)

From

Phase Diagram (V, Vs, Vv, Vw, Va)

Strength

strong

Relationship

Porosity is another void expression derived from phase diagram volumes

To

Porosity (n)

From

Void Ratio (e)

Strength

strong

Relationship

They are mathematically interconvertible: e = n/(1-n) and n = e/(1+e)

To

Degree of Saturation (S)

From

Water Content (w = Ww/Ws)

Strength

strong

Relationship

Both describe soil water presence; linked through master identity Se = wGs

To

Void Ratio (e)

From

Master Identity (Se = wGs)

Strength

strong

Relationship

Master identity allows calculation of e when S, w, Gs are known

To

Water Content (w)

From

Master Identity (Se = wGs)

Strength

strong

Relationship

Master identity allows calculation of w when S, e, Gs are known

To

Degree of Saturation (S)

From

Master Identity (Se = wGs)

Strength

strong

Relationship

Master identity allows calculation of S when e, w, Gs are known

To

Dry Unit Weight (γdry = Gs·γw/(1+e))

From

Specific Gravity (Gs)

Strength

strong

Relationship

Gs is essential input parameter in unit weight formula

To

Dry Unit Weight (γdry)

From

Void Ratio (e)

Strength

strong

Relationship

γdry inversely proportional to e; larger voids give lower dry density

To

Moist Unit Weight (γ = γdry(1+w))

From

Water Content (w)

Strength

strong

Relationship

Moist unit weight increases linearly with water content

To

Saturated Unit Weight (γsat = (Gs+e)γw/(1+e))

From

Degree of Saturation (S = 1)

Strength

strong

Relationship

At S = 1, all voids are water-filled; γsat is maximum unit weight

To

Submerged Unit Weight (γ' = γsat - γw)

From

Saturated Unit Weight (γsat)

Strength

strong

Relationship

Buoyant unit weight is saturated weight minus water weight; used in effective stress

To

Saturated Unit Weight (γsat)

From

Void Ratio (e)

Strength

moderate

Relationship

Larger void ratio reduces γsat due to increased water and air volume proportions

To

Dry Unit Weight (γdry)

From

Degree of Saturation (S = 0)

Strength

strong

Relationship

Dry soil condition with S = 0; γdry is minimum possible unit weight

To

Soil Classification

From

Phase Ratios (e, n, w, S, Gs)

Strength

moderate

Relationship

Phase ratios characterize soil types and saturation states used in USCS and engineering classification

To

Geotechnical Design (Foundations, Embankments, Pavements)

From

Unit Weights (γdry, γ, γsat, γ')

Strength

strong

Relationship

Unit weights are fundamental inputs for bearing capacity, settlement, and stability calculations

To

Effective Stress Principle

From

Effective Unit Weight (γ')

Strength

strong

Relationship

Submerged unit weight is used directly in effective stress calculations below water table

To

Specific Gravity (Gs)

From

Master Identity (Se = wGs)

Strength

strong

Relationship

Gs is a constant phase ratio term linking saturation, void ratio, and water content

To

All Unit Weight Formulas

From

Water Unit Weight (γw ≈ 9.81 kN/m³)

Strength

strong

Relationship

γw is the reference and scaling factor in all unit weight calculations

To

Problem-Solving Procedures

From

Phase Diagram and Ratios

Strength

strong

Relationship

Understanding phase relationships enables systematic solution of geotechnical problems