What Is the Rankine Passive Earth Pressure & Shear Key Calculator?
Passive earth pressure represents the maximum lateral soil resistance developed when a retaining wall foundation or embedded shear key is pushed horizontally into soil.
In retaining wall design, basal sliding resistance is often supplemented by passive resistance mobilized along the embedded toe and downward-projecting shear keys.
This calculator computes the Rankine passive coefficient Kp, horizontal passive thrust at the toe and shear key, and evaluates contribution to sliding stability.
How Does the Rankine Passive Earth Pressure & Shear Key Calculator Work?
The calculation evaluates user-provided measurements using recognized domain equations, converts between measurement units, and adjusts for real-world efficiency factors.
Rankine Passive Earth Pressure & Shear Key Calculator Formula & Variables
The core mathematical equation utilized by this calculator is expressed as:
Rankine passive earth pressure coefficient and total triangular passive resistance mobilized across toe and shear key embedment.
How to Use the Rankine Passive Earth Pressure & Shear Key Calculator
- Enter your primary measurements in the input fields above.
- Select your preferred units (e.g. metric or imperial) if applicable.
- Review or adjust operational assumptions such as field efficiency.
- Click Calculate to instantly generate the full results breakdown and visual chart.
- Use the Reset button at any time to clear the form and test a new scenario.
Step-by-Step Example Calculation
Cantilever Wall with Shear Key (φ = 32°, Df = 1.2m, d_key = 0.8m)
Input Values:
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
- Mobilizing full passive resistance requires horizontal wall movement of 1% to 5% of embedment depth. In design, passive thrust is typically derated by a factor of 1.5 to 2.0.
- Soil in front of the toe must be well compacted and protected against future frost or utility trench excavation.
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.