Bearing Capacity for Purely Cohesive Soil Calculator

Ultimate Bearing Capacity Formula:

\[ qf = (Cs \times Nc) + (σs \times Nq) \]

Cohesion of Soil:

Bearing Capacity Factor (Cohesion):

Effective Surcharge:

kPa

Bearing Capacity Factor (Surcharge):

Ultimate Bearing Capacity: Pa

1. What is Bearing Capacity for Purely Cohesive Soil?

Definition: This calculator determines the ultimate bearing capacity of purely cohesive soil using Terzaghi's bearing capacity equation.

Purpose: It helps geotechnical engineers and construction professionals assess the load-bearing capacity of cohesive soils for foundation design.

2. How Does the Calculator Work?

The calculator uses the formula:

\[ qf = (Cs \times Nc) + (σs \times Nq) \]

Where:

\( qf \) — Ultimate bearing capacity (Pa)
\( Cs \) — Cohesion of soil (Pa)
\( Nc \) — Bearing capacity factor for cohesion
\( σs \) — Effective surcharge (kPa)
\( Nq \) — Bearing capacity factor for surcharge

Explanation: The formula combines the soil's cohesive strength with the effect of any surcharge load above the foundation level.

3. Importance of Bearing Capacity Calculation

Details: Accurate bearing capacity estimation ensures foundation stability, prevents excessive settlement, and maintains structural integrity.

4. Using the Calculator

Tips: Enter soil cohesion, bearing capacity factors (default values provided), and effective surcharge. All values must be > 0. Results include ±5% tolerance.

5. Frequently Asked Questions (FAQ)

Q1: What is purely cohesive soil?
A: Purely cohesive soil (clay) derives its shear strength mainly from cohesion rather than internal friction.

Q2: Why ±5% tolerance?
A: The 5% accounts for typical variations in soil properties and measurement uncertainties.

Q3: What are typical Nc and Nq values?
A: For cohesive soils, Nc is typically 5.7-9, and Nq is typically 1-2.5 depending on conditions.

Q4: How is effective surcharge determined?
A: It's the vertical stress at foundation level from any soil or load above the foundation base.

Q5: Does this include safety factors?
A: No, the result is ultimate capacity. Divide by appropriate safety factor (typically 2.5-3) for allowable capacity.