Soil Profile View
Loose Sand (ϕ ≈ 30°)

Loose Sand

Loose sand is a granular, non-cohesive soil with low density and relatively low shear strength. It is highly susceptible to liquefaction under seismic loading and requires careful foundation design. Shear strength is governed entirely by internal friction.

Friction Angle (ϕ)
28° - 30°
Cohesion (c)
0 kPa
Unit Weight (γ)
16 kN/m³
Permeability
High (10⁻² cm/s)
Failure Criterion
Mohr-Coulomb (τ = σ·tan ϕ)

Geotechnical Reference Table (Typical Values)

τ = c + σ·tan ϕ
Soil TypeFriction (ϕ)Cohesion (c)Unit Weight (γ)Classification
Loose SandCurrent28° - 30°0 kPa16 kN/m³Cohesionless
Dense Sand36° - 40°0 kPa19 kN/m³Cohesionless
Soft Clay0° (φᵤ = 0)10 - 25 kPa17 kN/m³Cohesive
Stiff Clay18° - 25°50 - 150 kPa20 kN/m³Cohesive
Gravel35° - 45°0 kPa20 kN/m³Cohesionless
Silt22° - 30°5 - 10 kPa18 kN/m³Mixed
Silty Clay15° - 22°20 - 40 kPa19 kN/m³Mixed
Weathered Rock35° - 50°100 - 500 kPa24 kN/m³Rock Mass
Soil Profile View
Dense Sand (ϕ ≈ 38°)

Dense Sand

Dense sand has been compacted or naturally deposited to a high density, providing excellent bearing capacity and low compressibility. It exhibits dilatant behavior during shear and is one of the most reliable granular foundation soils.

Friction Angle (ϕ)
36° - 40°
Cohesion (c)
0 kPa
Unit Weight (γ)
19 kN/m³
Permeability
High (10⁻² cm/s)
Failure Criterion
Mohr-Coulomb (τ = σ·tan ϕ)

Geotechnical Reference Table (Typical Values)

τ = c + σ·tan ϕ
Soil TypeFriction (ϕ)Cohesion (c)Unit Weight (γ)Classification
Loose Sand28° - 30°0 kPa16 kN/m³Cohesionless
Dense SandCurrent36° - 40°0 kPa19 kN/m³Cohesionless
Soft Clay0° (φᵤ = 0)10 - 25 kPa17 kN/m³Cohesive
Stiff Clay18° - 25°50 - 150 kPa20 kN/m³Cohesive
Gravel35° - 45°0 kPa20 kN/m³Cohesionless
Silt22° - 30°5 - 10 kPa18 kN/m³Mixed
Silty Clay15° - 22°20 - 40 kPa19 kN/m³Mixed
Weathered Rock35° - 50°100 - 500 kPa24 kN/m³Rock Mass
Soil Profile View
Soft Clay (cᵤ ≈ 15 kPa)

Soft Clay

Soft clay is a highly compressible, low-permeability soil with significant cohesion but negligible internal friction under undrained conditions. Settlement occurs slowly through consolidation, requiring preloading or ground improvement techniques.

Friction Angle (ϕ)
0° (φᵤ = 0)
Cohesion (c)
10 - 25 kPa
Unit Weight (γ)
17 kN/m³
Permeability
Very Low (10⁻⁷ cm/s)
Failure Criterion
Undrained (τ = cᵤ)

Geotechnical Reference Table (Typical Values)

τ = c + σ·tan ϕ
Soil TypeFriction (ϕ)Cohesion (c)Unit Weight (γ)Classification
Loose Sand28° - 30°0 kPa16 kN/m³Cohesionless
Dense Sand36° - 40°0 kPa19 kN/m³Cohesionless
Soft ClayCurrent0° (φᵤ = 0)10 - 25 kPa17 kN/m³Cohesive
Stiff Clay18° - 25°50 - 150 kPa20 kN/m³Cohesive
Gravel35° - 45°0 kPa20 kN/m³Cohesionless
Silt22° - 30°5 - 10 kPa18 kN/m³Mixed
Silty Clay15° - 22°20 - 40 kPa19 kN/m³Mixed
Weathered Rock35° - 50°100 - 500 kPa24 kN/m³Rock Mass
Soil Profile View
Stiff Clay (c ≈ 100 kPa)

Stiff Clay

Stiff clay is an overconsolidated clay with high shear strength and low compressibility. It exhibits both cohesion and friction components, making it suitable for most foundation types. It can swell or shrink with moisture changes.

Friction Angle (ϕ)
18° - 25°
Cohesion (c)
50 - 150 kPa
Unit Weight (γ)
20 kN/m³
Permeability
Low (10⁻⁶ cm/s)
Failure Criterion
Mohr-Coulomb (τ = c + σ·tan ϕ)

Geotechnical Reference Table (Typical Values)

τ = c + σ·tan ϕ
Soil TypeFriction (ϕ)Cohesion (c)Unit Weight (γ)Classification
Loose Sand28° - 30°0 kPa16 kN/m³Cohesionless
Dense Sand36° - 40°0 kPa19 kN/m³Cohesionless
Soft Clay0° (φᵤ = 0)10 - 25 kPa17 kN/m³Cohesive
Stiff ClayCurrent18° - 25°50 - 150 kPa20 kN/m³Cohesive
Gravel35° - 45°0 kPa20 kN/m³Cohesionless
Silt22° - 30°5 - 10 kPa18 kN/m³Mixed
Silty Clay15° - 22°20 - 40 kPa19 kN/m³Mixed
Weathered Rock35° - 50°100 - 500 kPa24 kN/m³Rock Mass
Soil Profile View
Gravel (ϕ ≈ 40°)

Gravel

Gravel consists of coarse, angular or rounded particles with excellent drainage characteristics and very high shear strength. It provides outstanding bearing capacity and is widely used as foundation material and structural fill.

Friction Angle (ϕ)
35° - 45°
Cohesion (c)
0 kPa
Unit Weight (γ)
20 kN/m³
Permeability
Very High (10⁻¹ cm/s)
Failure Criterion
Mohr-Coulomb (τ = σ·tan ϕ)

Geotechnical Reference Table (Typical Values)

τ = c + σ·tan ϕ
Soil TypeFriction (ϕ)Cohesion (c)Unit Weight (γ)Classification
Loose Sand28° - 30°0 kPa16 kN/m³Cohesionless
Dense Sand36° - 40°0 kPa19 kN/m³Cohesionless
Soft Clay0° (φᵤ = 0)10 - 25 kPa17 kN/m³Cohesive
Stiff Clay18° - 25°50 - 150 kPa20 kN/m³Cohesive
GravelCurrent35° - 45°0 kPa20 kN/m³Cohesionless
Silt22° - 30°5 - 10 kPa18 kN/m³Mixed
Silty Clay15° - 22°20 - 40 kPa19 kN/m³Mixed
Weathered Rock35° - 50°100 - 500 kPa24 kN/m³Rock Mass
Soil Profile View
Silt (ϕ ≈ 26°)

Silt

Silt is a fine-grained soil with properties between sand and clay. It has low plasticity, moderate permeability, and can be problematic when saturated due to frost susceptibility and potential liquefaction in loose states.

Friction Angle (ϕ)
22° - 30°
Cohesion (c)
5 - 10 kPa
Unit Weight (γ)
18 kN/m³
Permeability
Moderate (10⁻⁴ cm/s)
Failure Criterion
Mohr-Coulomb (τ = c + σ·tan ϕ)

Geotechnical Reference Table (Typical Values)

τ = c + σ·tan ϕ
Soil TypeFriction (ϕ)Cohesion (c)Unit Weight (γ)Classification
Loose Sand28° - 30°0 kPa16 kN/m³Cohesionless
Dense Sand36° - 40°0 kPa19 kN/m³Cohesionless
Soft Clay0° (φᵤ = 0)10 - 25 kPa17 kN/m³Cohesive
Stiff Clay18° - 25°50 - 150 kPa20 kN/m³Cohesive
Gravel35° - 45°0 kPa20 kN/m³Cohesionless
SiltCurrent22° - 30°5 - 10 kPa18 kN/m³Mixed
Silty Clay15° - 22°20 - 40 kPa19 kN/m³Mixed
Weathered Rock35° - 50°100 - 500 kPa24 kN/m³Rock Mass
Soil Profile View
Silty Clay (c ≈ 30 kPa)

Silty Clay

Silty clay combines the cohesive properties of clay with the lower plasticity of silt. It has moderate shear strength and intermediate permeability, making it a common but variable foundation soil requiring site-specific investigation.

Friction Angle (ϕ)
15° - 22°
Cohesion (c)
20 - 40 kPa
Unit Weight (γ)
19 kN/m³
Permeability
Low (10⁻⁵ cm/s)
Failure Criterion
Mohr-Coulomb (τ = c + σ·tan ϕ)

Geotechnical Reference Table (Typical Values)

τ = c + σ·tan ϕ
Soil TypeFriction (ϕ)Cohesion (c)Unit Weight (γ)Classification
Loose Sand28° - 30°0 kPa16 kN/m³Cohesionless
Dense Sand36° - 40°0 kPa19 kN/m³Cohesionless
Soft Clay0° (φᵤ = 0)10 - 25 kPa17 kN/m³Cohesive
Stiff Clay18° - 25°50 - 150 kPa20 kN/m³Cohesive
Gravel35° - 45°0 kPa20 kN/m³Cohesionless
Silt22° - 30°5 - 10 kPa18 kN/m³Mixed
Silty ClayCurrent15° - 22°20 - 40 kPa19 kN/m³Mixed
Weathered Rock35° - 50°100 - 500 kPa24 kN/m³Rock Mass
Soil Profile View
Weathered Rock (c ≈ 300 kPa)

Weathered Rock

Weathered rock is a highly fractured and decomposed rock mass that retains some intact rock strength while exhibiting soil-like behavior. It provides very high bearing capacity but requires careful assessment of discontinuities.

Friction Angle (ϕ)
35° - 50°
Cohesion (c)
100 - 500 kPa
Unit Weight (γ)
24 kN/m³
Permeability
Variable (fracture-dependent)
Failure Criterion
Hoek-Brown / Mohr-Coulomb

Geotechnical Reference Table (Typical Values)

τ = c + σ·tan ϕ
Soil TypeFriction (ϕ)Cohesion (c)Unit Weight (γ)Classification
Loose Sand28° - 30°0 kPa16 kN/m³Cohesionless
Dense Sand36° - 40°0 kPa19 kN/m³Cohesionless
Soft Clay0° (φᵤ = 0)10 - 25 kPa17 kN/m³Cohesive
Stiff Clay18° - 25°50 - 150 kPa20 kN/m³Cohesive
Gravel35° - 45°0 kPa20 kN/m³Cohesionless
Silt22° - 30°5 - 10 kPa18 kN/m³Mixed
Silty Clay15° - 22°20 - 40 kPa19 kN/m³Mixed
Weathered RockCurrent35° - 50°100 - 500 kPa24 kN/m³Rock Mass