Effective Surcharge given Bearing Capacity of Non Cohesive Soil for Strip Footing Calculator

Effective Surcharge Formula:

\[ \sigma_s = \frac{q_{fc} - (0.5 \times \gamma \times B \times N_{\gamma})}{N_q} \]

Ultimate Bearing Capacity in Soil (kPa):

Unit Weight of Soil (kN/m³):

Width of Footing (m):

Bearing Capacity Factor (Nγ):

Bearing Capacity Factor (Nq):

Effective Surcharge (kPa):

1. What is Effective Surcharge?

Definition: Effective Surcharge in KiloPascal also called as surcharge load refers to the vertical pressure or any load that acts over the ground surface additional to basic earth pressure.

Purpose: It helps geotechnical engineers determine the additional load on soil for foundation design.

2. How Does the Calculator Work?

The calculator uses the formula:

\[ \sigma_s = \frac{q_{fc} - (0.5 \times \gamma \times B \times N_{\gamma})}{N_q} \]

Where:

\( \sigma_s \) — Effective Surcharge (kPa)
\( q_{fc} \) — Ultimate Bearing Capacity in Soil (kPa)
\( \gamma \) — Unit Weight of Soil (kN/m³)
\( B \) — Width of Footing (m)
\( N_{\gamma} \) — Bearing Capacity Factor dependent on Unit Weight
\( N_q \) — Bearing Capacity Factor dependent on Surcharge

Explanation: The formula calculates the effective surcharge by accounting for soil weight, footing dimensions, and bearing capacity factors.

3. Importance of Effective Surcharge Calculation

Details: Proper calculation ensures safe foundation design by considering all vertical loads acting on the soil.

4. Using the Calculator

Tips: Enter all required parameters with ±5% accuracy. Typical values are provided as defaults.

5. Frequently Asked Questions (FAQ)

Q1: What is typical value for Nγ?
A: For non-cohesive soils, Nγ typically ranges from 0.1 to 1.8 depending on soil type and conditions.

Q2: How do I determine Nq?
A: Nq depends on soil friction angle and can be found in geotechnical engineering references.

Q3: What units should I use?
A: Use consistent units: kN/m³ for unit weight, meters for dimensions, and kPa for pressure.

Q4: Can this be used for cohesive soils?
A: This formula is specifically for non-cohesive soils. Different factors apply for cohesive soils.

Q5: Why the ±5% margin?
A: Soil properties naturally vary, so a 5% margin accounts for typical measurement uncertainties.