Start with the design decision
Establish whether the objective is concrete continuity, an expected length or a casting anomaly. These questions need different information, not a test selected solely because it is available.
Link each question to specific piles and records. Integrity and load-bearing capacity remain distinct; project decisions require more than one signal.
Access and construction stage
CSL requires accessible paths through installed tubes. PIT and TRM require pile-head working conditions suitable for the test, with existing connections and restraints considered.
Early planning avoids requesting an impractical configuration late in construction. Check access, tube or head conditions and geometric information before choosing.
Required information and coverage
CSL examines tube-to-tube paths; PIT interprets time-domain reflections; TRM considers force–velocity relationships in frequency. These are not equivalent representations of one volume.
The table compares opportunities and limitations, not automatic acceptance criteria. A second method is justified if it can clarify uncertainty and the site permits a meaningful measurement.
Campaign planning and deliverables
Agree identifiers, objectives, preparation and treatment of unreadable signals before testing. Do not set generic thresholds outside the project’s technical and contractual documentation.
Deliverables should explain coverage, conditions, assumptions and limitations. An uncertain finding may need further records or investigation, not a forced classification.
Comparison by survey objective
| Method | Principle | Access | Execution stage | Information obtainable | Main limitations | Typical applications |
|---|---|---|---|---|---|---|
| Cross-Hole / CSL | Ultrasonic transmission between probes | Installed, traversable tubes | Planned before casting; measurement with accessible tubes | Signal variations by path and depth | Tube-to-tube coverage; coupling or tube problems | Investigation of concrete along installed paths |
| PIT / PEM | Low-strain impulse reflections | Accessible, suitable head | When the head is available and concrete suitable | Reflections, estimated length and impedance changes | Assumed velocity, attenuation, geometry and restraints | Dimensional assessment and head-based anomaly investigation |
| Mechanical admittance / TRM | Velocity/force relationship in frequency | Suitable head; force and response acquisition | When consistent impact and measurement are possible | Resonances, dimensional indications and inferred profile | Interpretive model, ground and boundary conditions | Frequency-domain vibrational investigation |
Related guides
Frequently asked questions
- Do integrity tests measure load-bearing capacity?
- No. They assess aspects of integrity or pile response within method limitations; they do not replace a load-capacity assessment.
- Which method is always best?
- None: the objective, access and pile conditions determine what information can be obtained.
- Is estimated length certain?
- No: it depends on velocity assumptions, identifying the response and boundary conditions.
References and documentary scope
What information does your project need?
Share the objective, site constraints and required deliverables so we can assess an appropriate survey strategy.
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