Factor of Safety given Unit Cohesion Calculator

Factor of Safety Formula:

\[ fs = \frac{cu \times Ls' \times d_{radial}}{W \times x'} \]

Unit Cohesion:

Length of Slip Arc with Factor of Safety:

Radial Distance:

Weight of Body in Newtons:

Distance between LOA and COR:

Factor of Safety:

1. What is Factor of Safety given Unit Cohesion?

Definition: This calculator determines the factor of safety for slopes or soil masses based on unit cohesion and other geotechnical parameters.

Purpose: It helps geotechnical engineers assess the stability of slopes and earth structures by comparing resisting forces to driving forces.

2. How Does the Calculator Work?

The calculator uses the formula:

\[ fs = \frac{cu \times Ls' \times d_{radial}}{W \times x'} \]

Where:

\( fs \) — Factor of Safety
\( cu \) — Unit Cohesion (%)
\( Ls' \) — Length of Slip Arc with Factor of Safety (%)
\( d_{radial} \) — Radial Distance (%)
\( W \) — Weight of Body in Newtons (%)
\( x' \) — Distance between LOA and COR (%)

Explanation: The numerator represents resisting forces (cohesion along slip surface), while the denominator represents driving forces (weight and moment arm).

3. Importance of Factor of Safety Calculation

Details: Proper safety factor estimation ensures slope stability, prevents landslides, and maintains structural integrity of earthworks.

4. Using the Calculator

Tips: Enter all parameters as percentages. Typical values range from ±5% of nominal values. All inputs must be greater than 0.

5. Frequently Asked Questions (FAQ)

Q1: What is a good factor of safety value?
A: Typically 1.3-1.5 for temporary works, 1.5-2.0 for permanent structures, depending on consequences of failure.

Q2: Why are all inputs in percentages?
A: Percentage inputs allow for relative comparisons and account for measurement uncertainties (±5%).

Q3: How does unit cohesion affect safety factor?
A: Higher cohesion increases the numerator, resulting in higher safety factor (more stable slope).

Q4: What if I get a safety factor below 1?
A: Values <1 indicate unstable conditions requiring redesign or reinforcement.

Q5: How accurate is this calculation?
A: It provides a preliminary estimate; detailed analysis should consider additional factors like pore pressure.