Calculation Of Support Capacity

Terzaghi Bearing Capacity Equation:

\[ Bearing\ Capacity = c \times N_c + \gamma \times D \times N_q + 0.5 \times \gamma \times B \times N_\gamma \]

Cohesion (c):

kPa

Bearing Factor N_c:

Unit Weight (γ):

kN/m³

Depth (D):

Bearing Factor N_q:

Width (B):

Bearing Factor N_γ:

Bearing Capacity:

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1. What is the Terzaghi Bearing Capacity Equation?

The Terzaghi bearing capacity equation is a fundamental formula in geotechnical engineering that calculates the ultimate bearing capacity of soil. It provides the maximum pressure that soil can withstand before failure occurs, considering soil cohesion, unit weight, and foundation dimensions.

2. How Does the Calculator Work?

The calculator uses the Terzaghi bearing capacity equation:

\[ Bearing\ Capacity = c \times N_c + \gamma \times D \times N_q + 0.5 \times \gamma \times B \times N_\gamma \]

Where:

\( c \) — Cohesion of soil (kPa)
\( N_c \) — Bearing capacity factor for cohesion
\( \gamma \) — Unit weight of soil (kN/m³)
\( D \) — Depth of foundation (m)
\( N_q \) — Bearing capacity factor for surcharge
\( B \) — Width of foundation (m)
\( N_\gamma \) — Bearing capacity factor for soil weight

Explanation: The equation combines three components: cohesion term, surcharge term, and soil weight term to determine the total bearing capacity.

3. Importance of Bearing Capacity Calculation

Details: Accurate bearing capacity calculation is crucial for foundation design, ensuring structural stability, preventing settlement failures, and optimizing construction costs.

4. Using the Calculator

Tips: Enter all required parameters with appropriate units. Ensure bearing capacity factors are selected based on soil type and foundation conditions. All values must be non-negative.

5. Frequently Asked Questions (FAQ)

Q1: What are typical values for bearing capacity factors?
A: Bearing capacity factors depend on soil friction angle. Typical values range from 5-50 for N_c, 1-40 for N_q, and 0-40 for N_γ.

Q2: How does foundation shape affect bearing capacity?
A: Shape factors should be applied for non-strip foundations. The equation shown is for continuous footings; modifications are needed for square or circular foundations.

Q3: What safety factors are typically used?
A: Safety factors of 2.5-3.0 are commonly applied to the ultimate bearing capacity to obtain allowable bearing capacity.

Q4: When is the Terzaghi equation not applicable?
A: The equation has limitations for layered soils, slopes, eccentric loading, and dynamic loading conditions.

Q5: How do water table conditions affect bearing capacity?
A: Submerged conditions reduce effective unit weight, which decreases bearing capacity. Appropriate corrections must be applied for water table effects.