Bearing Capacity & Pile Capacity Calculations on the PE Geotechnical Exam
Bearing capacity and pile capacity carry up to 30% of the PE Geotechnical exam. Three worked NCEES-style problems — Terzaghi shallow footing, alpha-method pile in clay, and pile-group block-failure check — plus the Meyerhof bearing-capacity factor table.
Foundations are the highest-weight calculation topic on the PE Civil Geotechnical exam. Per the NCEES April 2024 specification, Topic 9 (Shallow Foundations, ASD or LRFD) carries 6–9 questions and Topic 10 (Deep Foundations, ASD or LRFD) carries 10–15. Combined, that's 16–24 questions out of 80 — up to 30% of the exam hinging on bearing-capacity and pile-capacity calculations. No other topic block carries that much weight.
The good news: most foundation problems on the exam are direct calculation questions. The Terzaghi general bearing-capacity equation and the alpha / beta methods for pile axial capacity are reproduced in the NCEES PE Civil Reference Handbook. The skill the exam tests isn't formula recall — it's getting the inputs right (effective stress vs. total stress, drained vs. undrained, gross vs. net), picking the right shape factor for square / strip / circular footings, and remembering which method applies to which soil type.
Why foundations dominate the PE Geotechnical exam
The April 2024 NCEES PE Civil Geotechnical specification puts foundations at the top of the exam blueprint. Topic 9 and Topic 10 together take up 16–24 questions out of 80 — more than soil mechanics and lab testing (Topic 2, 8–12 questions), more than retaining structures (Topic 8, 10–15), more than earth structures (Topic 5, 9–14). If you can reliably solve the standard bearing-capacity and pile-capacity problems, you've put a substantial fraction of a passing score on the table before exam day.
The other reason foundations dominate: they connect to almost every other geotechnical concept. Bearing capacity needs effective stress (Topic 2A), unit weight (Topic 2A), and friction angle or undrained shear strength (Topic 2C). Pile capacity in clay needs adhesion factors that depend on soil classification (Topic 1F) and the SPT or CPT data from site characterization (Topic 1A–1E). A well-designed exam problem chains these together. Practicing foundations means practicing the whole geotech curriculum.
What the exam tests
At a high level, the exam tests whether you can size shallow footings and deep piles — the bearing capacity of a footing on sand or clay, the axial capacity of a pile driven through different soils, and the behavior of a pile group. The skill is choosing the right method for the soil and loading, getting the stress state and groundwater correction right, and reading whether the question wants an ultimate or an allowable answer.
Here are a couple of the problem types you'll face. The honest test: could you carry each one all the way to a defensible answer, in about six minutes, on exam day?
Worked example 1 — Terzaghi bearing capacity, square footing on sand. A 6-ft square footing is embedded 4 ft below the ground surface. The supporting sand has unit weight γ = 120 pcf, friction angle φ = 30°, cohesion c = 0. The water table is well below the footing (more than one footing-width below the base). Compute the ultimate and allowable bearing capacity using FS = 3.
Solution path: Identify the equation → Look up Meyerhof factors → Compute overburden pressure at the footing base → Substitute → Apply factor of safety.
Problems exactly like this are worked step by step on video in the PEwise PE Geotechnical course — every calculation, every unit conversion, and where the wrong answer choices come from.
Worked example 2 — Alpha-method pile in clay. A closed-end steel pipe pile, diameter D = 12 in (1.0 ft), is driven 50 ft into uniform medium clay with undrained shear strength su = 1500 psf. From the FHWA adhesion chart, α = 0.5 for su = 1500 psf. Compute the ultimate axial capacity and the allowable capacity at FS = 3.
Solution path: Unit skin friction (alpha-method) → Pile shaft surface area → Total skin friction → End-bearing unit resistance and tip area → End-bearing capacity → Total and allowable.
To see problems like this worked to the final answer on video, head to the PEwise PE Geotechnical course.
Worked example 3 — 3 × 3 pile group, block failure check. Continuing from Worked Example 2: a 3 × 3 group of the same piles (D = 1 ft, L = 50 ft, with the single-pile ultimate capacity Qult,single from Worked Example 2) is arranged with center-to-center spacing s = 3 ft (= 3D). The clay has su = 1,500 psf throughout. Compute the group ultimate capacity.
Solution path: Sum of individual pile capacities → Block dimensions → Block ultimate capacity → Group capacity is the smaller of the two → Allowable group capacity.
The PEwise PE Geotechnical course works problems like this end to end on video, with every intermediate value and a recap of the common slips.
The full methods behind these — the relationships, the procedures, and the mistakes that quietly cost points — are taught step by step in PEwise's PE Geotechnical course, with animated worked problems rather than a wall of formulas.
Foundations Are Where the Exam Is Won
PEwise's PE Geotechnical course walks through bearing capacity, alpha and beta methods, and pile group design with the same step-by-step rigor as the worked examples above — on real NCEES-style problems with detailed solutions.
Connecting this to your overall PE Geotechnical exam strategy
Foundations sit downstream of soil classification (Topic 1F) and soil mechanics / lab testing (Topic 2A–2C), and upstream of settlement, slope stability, and retaining-structure problems. Get the foundation calculations automatic, and the integrated questions become a sequence of clean steps rather than a puzzle. For the broader Topic 1 / Topic 2 fundamentals plus the full 24-module curriculum, our geotechnical PE exam study guide walks the syllabus end-to-end. For the slope-stability extension that pulls bearing capacity, lateral earth pressure, and shear strength into a single problem, see our slope-stability problem-types post.
Master Foundations with PEwise
PEwise's Modules 14 and 18 of the PE Geotechnical course (30+ lessons) cover bearing capacity for shallow foundations and axial-plus-lateral capacity for deep foundations with worked NCEES-style problems — including the alpha-method for clays and the beta-method for sands. Course author Mahdi Bahrampouri, Ph.D., Geotechnical Earthquake Engineer, built the curriculum directly against FHWA NHI-16-009 (Driven Piles), FHWA NHI-18-024 (Drilled Shafts), and the NCEES PE Civil Reference Handbook.
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