Unit Weight Of Soil Under Strip Footing For Case Of Local Shear Failure Calculator

Formula Used:

\[ \gamma = \frac{q_{nu} - \left(\frac{2}{3} \times C \times N_c + \sigma_s \times (N_q - 1)\right)}{0.5 \times B \times N_\gamma} \]

Net Ultimate BC (q_nu):

kPa

Cohesion in Soil (C):

kPa

Bearing Capacity Factor (N_c):

Effective Surcharge (σ_s):

kPa

Bearing Capacity Factor (N_q):

Width of Footing (B):

Bearing Capacity Factor (N_γ):

Unit Weight of Soil (γ):

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1. What is Unit Weight of Soil Under Strip Footing?

The unit weight of soil under strip footing refers to the weight per unit volume of soil that supports the foundation. It's a critical parameter in geotechnical engineering for determining the bearing capacity and stability of foundations, particularly in cases of local shear failure.

2. How Does the Calculator Work?

The calculator uses the formula:

\[ \gamma = \frac{q_{nu} - \left(\frac{2}{3} \times C \times N_c + \sigma_s \times (N_q - 1)\right)}{0.5 \times B \times N_\gamma} \]

Where:

\( \gamma \) — Unit Weight of Soil (kN/m³)
\( q_{nu} \) — Net Ultimate Bearing Capacity (kPa)
\( C \) — 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)
\( N_\gamma \) — Bearing Capacity Factor dependent on Unit Weight

Explanation: This formula calculates the unit weight of soil by considering various factors that contribute to the soil's bearing capacity under a strip footing, specifically for cases of local shear failure.

3. Importance of Unit Weight Calculation

Details: Accurate calculation of unit weight is crucial for foundation design, slope stability analysis, and determining the overall stability of soil structures. It helps engineers design safe and efficient foundations that can withstand applied loads without failure.

4. Using the Calculator

Tips: Enter all required parameters in appropriate units. Ensure values are positive and physically meaningful. The bearing capacity factors should be selected based on soil properties and failure conditions.

5. Frequently Asked Questions (FAQ)

Q1: What is local shear failure?
A: Local shear failure occurs when the soil fails gradually with significant settlement before complete failure, typically in medium-dense soils.

Q2: How do bearing capacity factors vary?
A: Bearing capacity factors depend on soil properties, particularly the angle of internal friction. Different values are used for general, local, and punching shear failures.

Q3: What is effective surcharge?
A: Effective surcharge refers to the additional vertical pressure acting on the ground surface beyond the basic soil pressure, which affects the bearing capacity.

Q4: When is this formula applicable?
A: This formula is specifically designed for strip footings experiencing local shear failure conditions in cohesive-frictional soils.

Q5: What are typical unit weight values for soils?
A: Unit weight typically ranges from 16-22 kN/m³ for most soils, with clay soils generally having higher values than sandy soils.