Classification of Piles Based on the Results of Low Strain Pile Integrity Tests - Case Studies of Selected Piles in Lagos and Port-Harcourt, Nigeria-Article

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The study evaluates low-strain pile integrity testing (LSPIT) on bored piles (BPs) and continuous-flight-auger piles (ACIPs) at industrial sites in Lagos and Port Harcourt, Nigeria. Using a wireless pile integrity tester, the authors analyzed stress-wave reflections to assess pile length and identify changes in shaft integrity.

The paper proposes seven interpretation categories: AA indicates a sound shaft with a clear pile-toe reflection; AB indicates no major anomaly but no clear toe reflection; ABx indicates no major anomaly detected to depth <em>x</em>; PFx indicates a probable anomaly at depth <em>x</em> with a clear toe reflection; PDx indicates a probable anomaly without a clear toe reflection; and IVx and IR describe inconclusive results for different reasons.

All four tested Lagos bored piles were classified AA and showed sound integrity, with toe depths around 14 m. In Port Harcourt, five ACIPs were classified as one AA, two AB, one PD10, and one PF2. The latter two showed estimated impedance reductions of 5–10% from about 10 m and 10% from about 2 m, respectively. Across both sites, approximately 78% of tested piles were assessed as structurally sound; the remaining 22% showed minor impedance changes, generally in ACIPs, suggesting possible small necking, voids, or soil intrusion without severe structural impact.

The authors conclude that the expanded classification provides more detail about where anomalies occur than earlier schemes. LSPIT findings should be considered alongside soil investigations, installation records, structural design information, and load tests—not used alone to accept or reject foundations.

Keywords

low-strain pile integrity testing

LSPIT

bored piles

continuous-flight-auger piles

wireless pile integrity tester

stress-wave reflections

pile integrity classification

impedance reduction

foundation assessment

Nigeria