Net Ultimate Bearing Capacity For General Shear Failure Calculator

Formula Used:

\[ q_{nu} = (C \times N_c) + (\sigma_s \times (N_q - 1)) + (0.5 \times B \times \gamma \times N_\gamma) \]

Cohesion in Soil as Kilopascal (C):

kPa

Bearing Capacity Factor dependent on Cohesion (N_c):

Effective Surcharge in KiloPascal (σ_s):

kPa

Bearing Capacity Factor dependent on Surcharge (N_q):

Width of Footing (B):

Unit Weight of Soil (γ):

N/m³

Bearing Capacity Factor dependent on Unit Weight (N_γ):

Net Ultimate Bearing Capacity (q_nu):

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1. What is Net Ultimate Bearing Capacity?

Net Ultimate Bearing Capacity is the minimum net pressure intensity that causes shear failure in soil. It represents the maximum pressure that the soil can withstand without failure under a foundation.

2. How Does the Calculator Work?

The calculator uses the general bearing capacity formula:

\[ q_{nu} = (C \times N_c) + (\sigma_s \times (N_q - 1)) + (0.5 \times B \times \gamma \times N_\gamma) \]

Where:

\( C \) — Cohesion in soil (kPa)
\( N_c \) — Bearing capacity factor dependent on cohesion
\( \sigma_s \) — Effective surcharge (kPa)
\( N_q \) — Bearing capacity factor dependent on surcharge
\( B \) — Width of footing (m)
\( \gamma \) — Unit weight of soil (N/m³)
\( N_\gamma \) — Bearing capacity factor dependent on unit weight

Explanation: The formula accounts for three main components contributing to soil bearing capacity: cohesion, surcharge, and soil weight.

3. Importance of Bearing Capacity Calculation

Details: Accurate bearing capacity calculation is crucial for foundation design, ensuring structural stability and preventing settlement or failure of structures built on soil.

4. Using the Calculator

Tips: Enter all required parameters with appropriate units. Ensure values are positive and within reasonable ranges for accurate results.

5. Frequently Asked Questions (FAQ)

Q1: What is the difference between net and gross bearing capacity?
A: Net bearing capacity excludes the overburden pressure, while gross bearing capacity includes it.

Q2: How are bearing capacity factors determined?
A: Bearing capacity factors are derived from soil mechanics theory and depend on soil friction angle and other properties.

Q3: When is this formula applicable?
A: This formula is specifically for general shear failure conditions in cohesive-frictional soils.

Q4: What safety factors should be applied?
A: Typical safety factors range from 2.5 to 3.5 depending on soil conditions and importance of structure.

Q5: Are there limitations to this equation?
A: The formula assumes homogeneous soil conditions and may not be accurate for layered soils or special foundation shapes.