Horses for Courses: Testing of Existing Foundations for Potential Reuse-PPT Presentation

PPT Presentation

Pdf Summary

The panel examined how to select the most appropriate test for evaluating existing foundations for potential reuse. Although testing technology has advanced, no method is suitable for every situation; choosing based on cost alone can overlook important limitations. Results should be interpreted by trained, experienced specialists, supported—but not directed—by software, and independently of who commissions the work.

Reusing foundations can save time and money, reduce construction impacts, and benefit projects in constrained or environmentally sensitive areas. Reuse is appropriate when the foundations’ condition and capacity, project demands, feasibility, risks, and expected service life make it a better option than a new system. Key uncertainties include limited historical records, changes in ground conditions, unknown loading history, and uncertainty about the foundations’ present condition and performance. Verification, risk thresholds, monitoring, and agreed acceptance of risk are therefore essential.

The panel covered three testing categories:

- <strong>Nondestructive testing:</strong> Impulse Echo and Impulse Response are fast but have limited penetration and can be affected by soil conditions, shaft geometry, or multiple reflectors. Parallel Seismic can estimate foundation depth and identify material, but requires a nearby borehole and is slower.
- <strong>Load testing:</strong> Dynamic, rapid, and static tests can assess capacity or settlement, but differ in access needs, test loads, disruption, and uncertainty. Existing piles may be difficult to test representatively; test results can depend on pile geometry and interpretation. Static testing can sometimes assess foundations while a structure remains in place, though available loads may be limited.
- <strong>Geophysical investigation:</strong> Methods such as Parallel Seismic, ground-penetrating radar, covermeters, soil borings, and surface-wave or refraction surveys can help establish foundation depth, reinforcement, and soil profile. Each has access or depth limitations; direct investigation may still be needed.

The overall message was to match the testing program to the project’s specific questions and risks, rather than assume one method can establish every aspect of foundation suitability.

Keywords

foundation reuse

testing methods

nondestructive testing

load testing

geophysical investigation

pile capacity

risk assessment

foundation verification

structural rehabilitation

soil conditions