Study guide
9.5 Deep Foundation Installation
NCEES PE Civil Construction Study Guide Exam
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1 Chapter 1: Soil Mechanics
1.1 Lateral Earth Pressure 1.2 Soil Consolidation and Settlement 1.3 Effective and Total Stresses 1.4 Bearing Capacity 1.5 Slope Stability
2 Chapter 2: Site Layout and Development
2.1 Layout and Control 2.2 Horizontal and Vertical Curves 2.3 Site Investigations and Utilities
3 Chapter 3: Material Properties
3.1 Soils, Rock, and Aggregates 3.2 Concrete Material Properties 3.3 Steel Material Properties 3.4 Wood Material Properties
4 Chapter 4: Estimating Quantities and Costs
4.1 Quantity Take-Off Methods 4.2 Cost Estimating 4.3 Engineering Economics 4.4 Work Measurement and Productivity (Earned Value)
5 Chapter 5: Project Planning and Scheduling
5.1 Construction Sequencing 5.2 Activity Time Analysis 5.3 Critical Path Method and Network Analysis 5.4 Resource Scheduling and Leveling 5.5 Time–Cost Trade-Off and Crashing
6 Chapter 6: Material Production, Execution, and Quality Control
6.1 Specification Conformance and Hold-Points 6.2 Field Testing: Concrete, Soils, and Aggregates 6.3 Compaction: Principles, Calculations, and Equipment 6.4 Concrete Placement, Consolidation, and Finishing 6.5 Bolting and Welding: Structural Steel Connections 6.6 Acceptance Sampling and Statistical Quality Control
7 Chapter 7: Structural Mechanics
7.1 Loads (Dead, Live, Construction, Wind, and Preloading) 7.2 Statics and Stresses (Bending, Shear, Deflection) 7.3 Beams, Columns, and Slabs 7.4 Foundation and Retaining Wall Mechanics
8 Chapter 8: Hydraulics and Hydrology
8.1 Stormwater Collection and Drainage (Open-Channel Flow) 8.2 Runoff Analysis 8.3 Detention and Retention Ponds
9 Chapter 9: Operations and Methods
9.1 Lifting and Rigging 9.2 Crane Capacity and Stability 9.3 Dewatering and Pumping 9.4 Equipment Selection and Production Rates 9.5 Deep Foundation Installation 9.6 Excavation and Embankment (Cut and Fill)
10 Chapter 10: Support of Construction Loads
10.1 Formwork Design 10.2 Falsework and Scaffolding 10.3 Shoring and Reshoring 10.4 Bracing and Anchorage 10.5 Support of Excavation (Trenching, Cofferdams) 10.6 Erection and Equipment Loads on Permanent Structures
11 Chapter 11: Health and Safety
11.1 OSHA Construction Regulations and Safety Management 11.2 Work Zone and Public Safety (Traffic Control)
9.5 Deep Foundation Installation
Key Takeaways Explain This Topic AI
Driven piles (steel, concrete, timber) are installed using impact or vibratory hammers and derive capacity from friction and end bearing.
The Engineering News Record (ENR) formula is a traditional dynamic formula used to estimate pile capacity based on hammer energy and pile set.
Drilled shafts (caissons) involve drilling a cylindrical hole and filling it with concrete; slurry or casing is used to keep the hole open in unstable soils.
A Pile Driving Analyzer (PDA) test is a dynamic test that measures strain and acceleration to verify pile capacity during driving.
Static load tests provide the most accurate measurement of foundation capacity but are expensive and time-consuming.
Last updated: July 2026
- Deep Foundation Installation
- Why This Topic Matters for the PE Construction Exam
When near-surface soils cannot support the loads of a structure, deep foundations are required to transfer loads to deeper, stronger strata (like bedrock or dense sand). The PE exam covers the means and methods of installing deep foundations, the equipment used, and the methods used to determine if the installed foundation meets the design capacity. Understanding the differences between driven piles and drilled shafts, and how to evaluate pile driving logs, is crucial.
Driven Piles
Driven piles are prefabricated elements pushed into the ground using high-energy impact hammers. They displace the soil, which can increase the density of surrounding granular soils but may cause heave in cohesive soils.
Pile Types
Steel H-Piles: Excellent for driving through hard layers or driving to bedrock for end-bearing capacity. They cause minimal soil displacement.
Steel Pipe Piles: Can be driven open-ended or closed-ended. Often filled with concrete after driving.
Precast Concrete Piles: Durable and cost-effective, but heavy and susceptible to damage (cracking or spalling) during hard driving.
Timber Piles: Traditional and economical for lighter loads, usually treated with preservatives.
Pile Hammers
Drop Hammers: A heavy weight lifted by a cable and dropped. Simple but slow.
Single-Acting Diesel/Air Hammers: Energy is used to lift the ram, and it falls by gravity.
Double-Acting Hammers: Energy is used to lift the ram and drive it downward, increasing the blow rate and energy transfer.
Vibratory Hammers: Uses rotating eccentric weights to vibrate the pile into the ground. Highly effective in loose sands but ineffective in stiff clays.
Pile Capacity and the ENR Formula
Historically, contractors and engineers used dynamic formulas to estimate the safe bearing capacity of a pile based on its resistance to driving (the "set" or penetration per blow). The most famous is the Engineering News Record (ENR) Formula .
While modern geotechnical engineering relies on wave equation analysis (WEAP), the ENR formula still appears in academic contexts and exams to demonstrate the relationship between hammer energy and pile capacity.
ENR Formula for Safe Bearing Capacity ( Q a Q_a Q a ): Q a = 2 ⋅ E S + C Q_a = \frac{2 \cdot E}{S + C} Q a = S + C 2 ⋅ E
Where:
Q a Q_a Q a = Safe load capacity (in lbs).
E E E = Energy per blow of the hammer (in ft-lbs). For a drop hammer, E = W ⋅ H E = W \cdot H E = W ⋅ H (Weight of ram × \times × Height of fall).
S S S = Average penetration (set) per blow for the last few blows (in inches).
C C C = Empirical constant (typically 1.0 for drop hammers and 0.1 for single-acting steam/air hammers).
Note: This formula already includes an implicit Factor of Safety of 6. The result is the safe (allowable) capacity, not the ultimate capacity.
Drilled Shafts (Caissons)
Drilled shafts (also known as bored piles or caissons) are installed by excavating a cylindrical hole, placing a rebar cage, and pouring concrete. Unlike driven piles, they do not displace the soil.
Construction Methods
Dry Method: Used in cohesive soils above the water table where the hole will stay open on its own without caving in.
Casing Method: A temporary steel pipe (casing) is driven or vibrated into the ground to hold back unstable soils or water. The hole is drilled inside the casing, concrete is poured, and the casing is extracted as the concrete rises.
Slurry Method (Wet Method): Used when the soil is highly unstable (e.g., loose sands below the water table). A viscous fluid (bentonite or polymer slurry) is pumped into the hole during drilling. The hydrostatic pressure of the slurry keeps the hole from collapsing. Concrete is pumped to the bottom of the hole using a tremie pipe, displacing the lighter slurry upwards.
Foundation Testing
Verifying that deep foundations can support the design loads is a critical quality control step.
Static Load Test: The most reliable method. A massive reaction frame or dead weights are placed over the pile, and hydraulic jacks apply a measured static load. Settlement is recorded. It is expensive and time-consuming.
Pile Driving Analyzer (PDA): A dynamic testing method. Sensors (strain gauges and accelerometers) are bolted to the pile during driving. They measure force and velocity during hammer impacts. The data is analyzed (often using CAPWAP software) to determine soil resistance, hammer efficiency, and pile integrity. It is much faster and cheaper than static tests.
Crosshole Sonic Logging (CSL): Used for drilled shafts. Tubes are cast into the concrete. A sonic transmitter is lowered down one tube and a receiver down another. The time it takes for sound to travel between the tubes indicates the quality of the concrete and detects voids or soil inclusions.