1. What is Bearing Capacity for Purely Cohesive Soil?

Definition: This calculator determines the ultimate bearing capacity of purely cohesive soil using the bearing capacity factor.

Purpose: It helps geotechnical engineers and construction professionals design foundations for cohesive soils like clay.

2. How Does the Calculator Work?

The calculator uses the formula:

Where:

• \( qf \) — Ultimate bearing capacity (Pascals)
• \( Cs \) — Cohesion of soil (Pascals)
• \( 5.7 \) — Bearing capacity factor for cohesive soil (±5%)
• \( \sigma s \) — Effective surcharge (converted from kPa to Pa)

Explanation: The cohesion is multiplied by the bearing capacity factor and added to the effective surcharge to determine the soil's load-bearing capacity.

3. Importance of Bearing Capacity Calculation

Details: Proper calculation ensures foundation stability, prevents settlement issues, and guarantees structural safety for buildings and infrastructure.

4. Using the Calculator

Tips: Enter the soil cohesion in Pascals, effective surcharge in kPa, and bearing capacity factor (default 5.7 ±5%). All values must be ≥ 0.

5. Frequently Asked Questions (FAQ)

Q1: What is purely cohesive soil?
A: Purely cohesive soil (like clay) has shear strength primarily from cohesion rather than internal friction.

Q2: Why is the bearing capacity factor 5.7?
A: 5.7 is the theoretical value for cohesive soils under strip footings, derived from Prandtl's solution (±5% variation possible).

Q3: How to measure soil cohesion?
A: Cohesion is typically determined through laboratory tests like unconfined compression or triaxial tests.

Q4: What affects effective surcharge?
A: Surcharge depends on overburden pressure from adjacent structures, backfill material, or surface loads.

Q5: When would I change the factor?
A: Different foundation shapes (square, circular) require adjusted factors (typically lower than 5.7).

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