Full-Service Pile Testing PDA · Static · Seismic to ASTM Standards

What is a Dynamic Load Test (PDA)?

A Dynamic Load Test, or PDA Test (Pile Driving Analyzer), is High Strain Dynamic Testing of pile load capacity per ASTM D4945 and DPT 1252-51. Strain gauges and accelerometers are installed on the pile near its head to record force and velocity as the hammer strikes the pile head. The PDA performs a preliminary analysis (Case Method) in real time, and the signals are then analyzed by signal matching with CAPWAP (Case Pile Wave Analysis Program) to find the ultimate pile capacity

Data from a PDA test

• Ultimate Pile Capacity—Maximum load capacity of the pile, split into skin friction and end bearing
• Driving Stress—Maximum compressive and tensile stresses in the pile during driving, used to prevent pile cracking or damage
• Hammer Efficiency—Efficiency of the pile driving hammer, used to check and improve driving
• Pile Integrity—Preliminary integrity check of the pile from the wave signals
• Set per Blow—Penetration per hammer blow, used to control when driving stops

Advantages of a Dynamic Load Test over a Static Load Test

A Dynamic Load Test can test several piles per day at a cost per pile many times lower than a Static Load Test (detailed Dynamic vs Static comparison), making it suitable for high-volume testing for quality control across a whole project. However, if a project needs the highest accuracy or the work is for research, the Static Load Test remains the gold standard, giving a Load-Settlement Curve under real compression

Projects suited to PDA testing

• Large projects with many piles that need fast QC, such as industrial estates, warehouses and factories
• Re-strike Test retesting after a set-up period to confirm the long-term capacity gained from soil setup
• Piles suspected of not reaching the bearing stratum, checked before deciding to drive further
• Space-constrained projects where a reaction system for a static test cannot be set up

What is a Static Load Test by the Kentledge Method?

A Static Load Test by the Kentledge Method is the most accurate pile load test. Concrete or steel blocks with a total weight of no less than the maximum test load (typically 200% of the design load) are stacked as a kentledge above the test pile. Load is applied through a hydraulic jack, and settlement is measured with dial gauges or linear transducers mounted on an independent reference beam, recorded at every load increment per ASTM D1143

Maintained Load Test (MLT) procedure

• Loading Phase—Load is increased in steps, typically 8–10 increments up to 200% of the design load, waiting for settlement to stabilize before the next increment
• Maintained Load—The maximum load is held for 24 hours, recording settlement throughout
• Unloading Phase—Load is reduced in steps, recording rebound
• Residual Settlement—Permanent settlement measured after full unloading

Projects suited to the Kentledge Method

• Projects with enough space for a kentledge stack, such as factories, warehouses and industrial estates
• Piles that need a Load-Settlement Curve for foundation design, or confirmation of capacity above 500 tons
• Critical works that require the highest reliability, such as power plants, oil depots and special structures

What is a Static Load Test by the Anchor Pile Method?

The Anchor Pile Method tests pile load capacity using anchor piles (reaction piles) to provide the reaction instead of dead weight. The setup consists of the test pile in the center, 2–4 anchor piles around it and a reaction beam connecting them. Load is applied through a hydraulic jack and settlement is measured from an independent reference beam, giving results equivalent to the Kentledge Method per ASTM D1143

Differences from the Kentledge Method

• No dead weight to transport—Greatly reduces kentledge transport and setup costs at remote sites
• Suits confined sites—No space needed for a large weight stack
• Highly flexible—Reaction layout can be adapted to site conditions
• Anchor piles must be designed—Anchor piles must have sufficient tensile capacity; uplift capacity must be considered

Projects suited to the Anchor Pile Method

• Sites where kentledge is hard to bring in, such as urban areas, under bridges or tight spaces
• Projects where anchor piles are installed together with production piles, saving significant cost
• Testing large bored piles without needing a very heavy kentledge

What is an Instrumented Static Load Test?

An Instrumented Static Load Test is a Static Load Test per ASTM D1143 with strain gauges installed at several levels along the pile before casting. At each load step, strain is read at every level and converted to force in the pile, showing how much load is transferred to the soil by skin friction in each soil layer and how much reaches the toe (end bearing) — information a standard Static Load Test cannot provide

Test deliverables

• Load Transfer Curve—Plot of pile force versus depth at every load step
• Unit skin friction per soil layer—Actual skin friction of each layer, compared with design values
• End Bearing—Bearing resistance at the pile toe
• Load–Settlement Curve—Same result as a standard Static Load Test

When is it worth doing?

• Projects with many piles, where data from a few test piles may be used to adjust pile lengths across the whole project
• Complex soil profiles, such as thick soft clay interbedded with sand, where design parameters are highly uncertain
• Long or heavily loaded piles, where the skin/toe resistance split strongly affects safety and construction cost

Requirements before testing

The decision must be made before the pile is cast, because the gauges are tied to the reinforcement cage and embedded in the concrete. Gauge levels are set to bracket the soil layer boundaries from the boring results, and the cables must be protected while lowering the cage and pouring concrete. See more instrumentation work at Instrumentation services

What is a Static Tension Pile Load Test?

A Static Tension Pile Load Test, or Uplift Test, measures the tensile (uplift) capacity of a pile by pulling it upward along its axis per ASTM D3689. A pile's tensile capacity comes mainly from skin friction between the pile and the soil, excluding end bearing at the toe

Test principle

The pile head is connected to a reaction frame with rods or strands linked to the beam structure. Tension is applied through a hydraulic jack, and upward displacement is measured with dial gauges or LVDTs mounted on an independent reference beam. A Load-Uplift Curve is recorded at each load increment up to 200% of the design tensile load

Projects that need a Tension Test

• High-voltage transmission towers—Piles carry very high tension from overturning moment and wind
• Floating structures and piers—Resist uplift from water and waves
• High-rise buildings in seismic zones—Corner piles take tension during earthquakes
• Earth-retaining anchors (anchor wall / tie-back)—Pullout capacity must be confirmed before use
• Underground oil storage and water tanks—Resist groundwater pressure that tends to lift the structure

What is a Lateral Pile Load Test?

A Lateral Pile Load Test measures a pile's horizontal load capacity and lateral deflection behavior per ASTM D3966. Load is applied through a hydraulic jack between the test pile and a reaction, which may be an adjacent pile, an excavator or an existing structure. Movement is measured with dial gauges or electronic displacement transducers with an independent reference beam

Test deliverables

• Load-Deflection Curve—Relationship between lateral load and deflection, used to verify the design
• Subgrade Reaction Modulus (p-y Curve)—Parameters for analyzing laterally loaded pile behavior
• Ultimate Lateral Capacity—Maximum lateral capacity before pile failure
• Bending Moment Profile—With strain gauges along the pile, the location of maximum moment can be identified

Projects that need a Lateral Load Test

• Bridge piers and elevated roadways—Resist horizontal braking, wind and seismic forces
• Piers and coastal structures—Resist ship impact and wave forces
• Piles in deep excavations—Confirm the lateral stiffness of the support system
• Buildings in seismic zones—Check pile behavior under seismic loads
• Retaining wall piles—Confirm the passive resistance of the soil

What is a Seismic Pile Integrity Test (PIT)?

The Seismic Pile Integrity Test, or Low Strain Integrity Test, is a non-destructive test of pile integrity per DPT 1551-51 and ASTM D5882-16 (withdrawn in 2025 — DPT is used as the main criterion). A light hammer taps the pile head, creating a stress wave that travels down the full pile length. The return signal is picked up by an accelerometer or velocity transducer and analyzed with PILE INTEGRITY TESTER (PIT-W) software to find the location and size of defects (read more: How to read Seismic Test results)

What a PIT test can detect

• Cracks—Pile cracked during driving or transport, shown as an early reflection on the plot
• Necking—Bored pile diameter reduced at some levels
• Pile joints—Splices between pile segments, checked for continuity
• Pile toe—Confirms pile length against the construction drawings
• Voids or poorly compacted concrete—In bored piles with substandard concrete quality

Limitations of PIT testing

PIT testing has limitations for piles with a length-to-diameter ratio (L/D) above 30, because the signal attenuates before reaching the toe, and it is not suited to detecting defects at very great depth. In such cases, CSL or Parallel Seismic testing is recommended in addition

Projects suited to PIT testing

• Testing all piles on a project after driving, for preliminary QC before casting footings
• Piles suspected of cracking or damage during driving
• Checking existing piles in building repair work before adding load
• Confirming pile length together with boring log data

What is a Side Echo Test?

The Side Echo Test is a side integrity test of piles developed from the standard Seismic Integrity Test, so that pile integrity can be tested when a sensor cannot be mounted on the pile head — for example, when a structure already sits above the test pile head. It assesses pile integrity and can also assess pile length (when a clear toe reflection is observed)

Test principle

• Excavate a pit beside the footing—Dig beside the footing or pedestal until the side surface of the pile below the footing is exposed
• Install the impact point and sensor—Fix a transfer block and an accelerometer to the side surface of the pile
• Tap and record signals—Tap with a hand hammer so a stress wave travels along the pile, and record the reflections with a Seismic Integrity Tester
• Analyze results—Interpret the reflectogram for anomalies in the pile, and the toe level when a clear reflection is found

What is it suited to?

• Piles with a footing, pedestal or structure already cast above the pile head
• Checking existing building piles before extending, repairing or adding load (see Existing pile assessment)
• Buildings with settlement or cracks that need the piles under the footings checked
• Preliminary length assessment of existing piles when a clear toe reflection is found

Limitations to note

A pit must be dug down to the side surface of the pile; if groundwater is high, it must be pumped out before testing. Reflections from the footing and the structure above can interfere with interpretation, making it harder to interpret than a standard Seismic Integrity Test at the pile head, and length can be assessed only when a clear toe reflection is seen — to confirm existing pile length directly, we recommend the Parallel Seismic Test (ASTM D8381)

What is Cross-Hole Sonic Logging (CSL)?

Cross-Hole Sonic Logging (CSL) is a non-destructive test of concrete quality in bored piles. Ultrasonic waves are sent from a transmitter probe in one water-filled access tube to a receiver probe in another, measuring the wave velocity and signal energy through the concrete, following ASTM D6760-16 (withdrawn by ASTM in 2025 with no replacement yet). ACI PRC-228.2 is currently referenced as the main guidance document. Results are presented as a waterfall plot and a velocity tomography map, accurately locating defects and their depth

Reading results — Good Signal / Delayed Signal / Blocked Signal

Received signals fall into 3 levels: Good Signal — the wave travels directly through normal concrete at high velocity, indicating sound concrete; Delayed Signal — the wave takes longer, indicating a partial defect in the concrete, such as small voids or segregation; and Blocked Signal — no signal or a very weak signal, indicating a large defect or void blocking the signal path

Projects suited to CSL testing

• Large bored piles / barrettes—Diameter 0.60 m and above, where concrete quality must be confirmed before the pile takes load
• Factories, warehouses and high-rise buildings—With special requirements from the design engineer or owner
• Piles with suspected construction problems—Such as slurry or water ingress during concreting
• Energy, petrochemical and infrastructure projects—That require quality assurance documentation

Prerequisites before testing

Piles must have access tubes (PVC or steel) installed in the reinforcement cage before concreting. The number of tubes depends on pile size (FHWA guidance: about 1 tube per 0.25–0.30 m of diameter, e.g. 3 tubes for ⌀ 0.80 m and 4 or more for large piles). Tubes must be filled with water before testing, and testing can be done at the earliest once the concrete is 7 days old

What is a Parallel Seismic Test?

A Parallel Seismic Test (PS Test) is a non-destructive test used to assess the length of piles or buried foundations (foundation depth assessment) without excavating. It is especially suited to old structures without as-built drawings, or piles whose heads cannot be accessed

Parallel Seismic test principle

A borehole is drilled 1–3 meters from the pile, deeper than the expected pile length. The pile head (or structure) is then struck to generate a stress wave, and the signal is received by a hydrophone or geophone lowered step by step in the borehole, recording the wave arrival time (travel time) at each depth. The velocity profile shows a clear change in wave velocity where the wave stops traveling through the pile and passes directly through the soil, which corresponds to the pile toe

Advantages of the Parallel Seismic Test

• Assesses pile length without excavating — minimizing damage to the existing structure
• Suits piles whose heads are buried under footings or concrete slabs
• Works with all foundation types — concrete, timber, steel and bored piles
• Supports assessment of special structures such as bridge piers, retaining walls, sheet piles and weirs
• Highly accurate results when combined with soil profile data from soil boring

When to use a Parallel Seismic Test

• Building repairs and extensions—Existing pile length must be known before designing for added load
• Structures without as-built drawings—Old buildings, bridges and piers whose drawings have been lost
• Assessment before demolition or renovation—Check whether existing piles can take additional load
• Bridges and irrigation structures—Assess foundation depth in hard-to-reach water
• Disputes and engineering litigation—Technical evidence to prove pile length

Parallel Seismic vs Seismic PIT

Seismic PIT (low strain) checks pile integrity — whether there are cracks or defects — but is limited in assessing the length of piles with a high length-to-diameter ratio (L/D > 30). Parallel Seismic is designed specifically for length assessment and gives more accurate results for long piles and complex foundations

What is an existing pile assessment?

An assessment of the footings and piles of a building in use, for buying a used factory or warehouse, extending a building, adding load, or buildings without construction drawings. SPN sets up a test package that answers the project's questions directly instead of testing everything — starting with an engineer's condition survey, then test pits to expose footings at representative points, followed by only the tests needed

Common test packages

• How long are the existing piles?—Parallel Seismic Test (ASTM D8381)
• Are piles cracked or necked?—Seismic Integrity Test (DPT 1551-51) where the pile head can be exposed, or Side Echo Test where a footing covers the pile head
• How deteriorated is the footing concrete?—Rebound Hammer (ASTM C805) + UPV (ASTM C597) — see non-destructive structural testing
• How much load can the soil carry?—Soil boring (ASTM D1586) to assess existing pile capacity

Deliverables

A report on footing condition, pile length and integrity at representative points, assessed load capacity, and recommendations for extension or foundation strengthening — certified by a licensed engineer and usable for purchase decisions or extension design

What is a Pile Bending Test?

A Pile Bending Test measures the bending moment capacity of precast prestressed concrete piles, such as I-piles, square piles or spun piles. The pile is placed on two supports as a simple span, and load is added in steps (step loading) using concrete dead-weight blocks or hydraulic jacks up to the specified test moment (proof load), measuring deflection and checking for cracks at every step

Test load criteria

The test moment is set by the project specifications or the design engineer, e.g. referencing the load test criteria of ACI 318-19 Chapter 27 or Engineering Institute of Thailand (EIT) criteria. SPN prepares calculations of the dead weight, placement positions and loading steps for the designer to review before testing

Test deliverables

• Load–Deflection Curve—Midspan deflection at every load step, and recovery after unloading
• Cracking Moment—Moment at which the first crack appears
• Crack width—Measured against the project's acceptance criteria

Work that needs bending tests

• Piles used as retaining walls along canals, riverbanks and drainage channels, mainly carrying bending
• Acceptance testing of precast piles before use, per project specifications
• Piles suspected of damage from lifting, handling or storage