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Bishop Simplified Circular Arc Slope Stability Safety Factor Calculator

Alan W. Bishop improved the Ordinary Method of Slices by satisfying vertical force equilibrium for each individual slice.

Total gravitational weight of soil slice

Mohr-Coulomb shear cohesion intercept

Effective internal friction angle

Horizontal width of slice

Angle of slice bottom slip arc tangent to horizontal

Pore pressure along slice base

Calculated Result
1.26

Bishop Factor of Safety (FS)

Stability Assessment

Critical / Marginal

Calculation Breakdown

  1. Bishop Simplified IterationFS = Σ[...] / Σ(W·sinα) => 1.26

Safety Factor vs Water Pressure

Interactive visualization based on your current inputs

FS
0.00.50.91.41.8Dry (u = 0)Moderate (u = 25)High (u = 50)Pore Pressure (kPa)Factor of Safety

What Is the Bishop Simplified Circular Arc Slope Stability Safety Factor Calculator?

Alan W. Bishop improved the Ordinary Method of Slices by satisfying vertical force equilibrium for each individual slice.

The non-linear m_alpha factor eliminates severe conservatism on deep circular rotational slip failure surfaces.

How Does the Bishop Simplified Circular Arc Slope Stability Safety Factor Calculator Work?

The calculation evaluates user-provided measurements using recognized domain equations, converts between measurement units, and adjusts for real-world efficiency factors.

Bishop Simplified Circular Arc Slope Stability Safety Factor Calculator Formula & Variables

The core mathematical equation utilized by this calculator is expressed as:

\text{FS} = \frac{\sum \frac{c' b + (W - u b) \tan\phi'}{m_\alpha}}{\sum W \sin\alpha}, \quad m_\alpha = \cos\alpha \left(1 + \frac{\tan\alpha \tan\phi'}{\text{FS}}\right)

Bishop iterative circular arc safety factor equation.

How to Use the Bishop Simplified Circular Arc Slope Stability Safety Factor Calculator

  1. Enter your primary measurements in the input fields above.
  2. Select your preferred units (e.g. metric or imperial) if applicable.
  3. Review or adjust operational assumptions such as field efficiency.
  4. Click Calculate to instantly generate the full results breakdown and visual chart.
  5. Use the Reset button at any time to clear the form and test a new scenario.

Step-by-Step Example Calculation

Highway Embankment Stability Slice

Input Values:

totalSliceWeightKnPerM:200.0
cohesionKpa:15.0
frictionAngleDeg:30.0
sliceWidthM:2.0
sliceBaseAngleDeg:30.0
porePressureKpa:30.0

Understanding Your Result

Your calculated result represents the realistic operational capacity or baseline output under the specified conditions. Comparing theoretical and effective outputs reveals the direct impact of turns, overlap, and practical downtime.

Factors That Affect the Result

Field terrain, operator experience, equipment maintenance, overlap margin, and weather conditions can significantly influence real-world output.

When Should You Use This Calculator?

Use this calculator whenever you need quick, verified estimates for job planning, budgeting, equipment sizing, or project timelines.

Assumptions & Limitations

  • Converges within 3 to 5 iterations for typical embankment geometries.

Frequently Asked Questions

Calculation Accuracy & Reference Note

This calculator implements verified, deterministic mathematical equations based on published standards. Results should be treated as professional engineering estimates; always verify critical operations with local equipment manuals and site inspections.

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