Civil Geotechnical Design Toolbox

Geotechnical calculators in one place

This bundle groups together the most common day-to-day checks a civil geotechnical engineer performs: shallow foundation bearing capacity, settlement, earth pressure on retaining walls, infinite slope stability, and seepage through soil. The calculators are intentionally simple and transparent so you can see the governing parameters and quickly test “what-if” scenarios.

These tools are ideal for preliminary design, sanity checks on software output, teaching, and exam preparation (e.g., FE/PE or other professional certifications). For final design, always follow your governing code (Eurocode 7, AASHTO, local standards) and a full geotechnical investigation.

Bearing capacity design workflow

1. Estimate soil parameters from lab tests or correlations (c′, φ′, γ).
2. Enter footing width and depth, including groundwater position.
3. Check the computed allowable bearing pressure against your applied service pressure.
4. If the factor of safety is too low, increase footing size, reduce load, or improve ground (e.g., compaction, replacement, deep foundations).

Settlement vs. bearing capacity

A footing can be safe in terms of ultimate bearing capacity but still experience excessive settlement. Use the settlement tab to estimate primary consolidation in soft clays. For sands, elastic or empirical methods are more appropriate and are not covered in this simple 1D consolidation model.

Earth pressure and wall design

The Rankine active earth pressure model assumes a vertical wall, horizontal backfill, and no wall friction. It is conservative for many practical retaining walls. For more complex geometries, surcharges, or wall–soil interaction, Coulomb or numerical methods are recommended.

Slope stability quick check

The infinite slope model is a first-order approximation for long, uniform slopes. It is useful to understand how groundwater, slope angle, and soil strength affect the factor of safety. For real projects, circular or non-circular slip surface analyses (e.g., Bishop, Janbu, limit equilibrium or FEM) are standard.

Limitations and good practice

• Use characteristic soil parameters with appropriate partial or global factors.
• Account for variability in stratigraphy, groundwater, and loading.
• Document assumptions clearly in your design notes.
• Have critical designs independently checked by another engineer.

FAQ: Civil geotechnical engineering basics

What is geotechnical engineering in civil engineering?

Geotechnical engineering is the branch of civil engineering focused on soil and rock behavior and their interaction with structures. It covers site investigation, laboratory testing, analysis, and design of foundations, retaining structures, slopes, embankments, tunnels, and earth dams.

What data do I need before using these calculators?

At minimum you should know the soil profile, unit weights, shear strength parameters (c, φ), groundwater level, and the geometry and loads of your structure. These are typically obtained from boreholes, in-situ tests (SPT, CPT), and lab tests (triaxial, oedometer, direct shear).

Can I use these tools for exam preparation?

Yes. The calculators implement standard textbook equations commonly examined in undergraduate geotechnical courses and professional exams. They are useful for checking hand calculations and building intuition about parameter sensitivity.

Are partial factors or LRFD included?

The calculators use global factors of safety by default. If you work under LRFD or partial factor frameworks, you can input factored loads and characteristic resistances, or back-calculate equivalent global factors. Always align your workflow with the specific requirements of your code.