Bearing Capacity for Purely Cohesive Soil given Unit Weight of Soil Calculator

Ultimate Bearing Capacity Formula:

\[ q_f = (5.7 \times C_s) + \sigma_s \]

Ultimate Bearing Capacity (kPa):

Safe Bearing Capacity (kPa):

1. What is Bearing Capacity for Purely Cohesive Soil?

Definition: This calculator determines the ultimate and safe bearing capacity of purely cohesive soil (clay) based on soil cohesion and effective surcharge.

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

2. How Does the Calculator Work?

The calculator uses the formula:

\[ q_f = (5.7 \times C_s) + \sigma_s \]

Where:

\( q_f \) — Ultimate bearing capacity (kPa)
\( C_s \) — Cohesion of soil (kPa)
\( \sigma_s \) — Effective surcharge (kPa)

Explanation: The formula accounts for soil cohesion (5.7 factor for purely cohesive soil) and additional load from surcharge.

3. Importance of Bearing Capacity Calculation

Details: Proper bearing capacity estimation ensures foundation stability and prevents soil failure under structural loads.

4. Using the Calculator

Tips: Enter soil cohesion (kPa), effective surcharge (kPa), and safety factor (%). Cohesion must be > 0, surcharge ≥ 0, safety factor ≥ 0.

5. Frequently Asked Questions (FAQ)

Q1: What is purely cohesive soil?
A: Soil (like clay) where shear strength comes mainly from cohesion rather than internal friction.

Q2: Why 5.7 factor for cohesion?
A: It's derived from bearing capacity theory for continuous footings in cohesive soil.

Q3: What is effective surcharge?
A: Additional vertical pressure at foundation level from surrounding soil or structures.

Q4: How is safety factor applied?
A: The ultimate capacity is reduced by the safety percentage (e.g., 5% reduction for 5% factor).

Q5: When is this formula applicable?
A: For continuous footings in saturated clay under undrained conditions (φ=0 analysis).