Revisiting Mansur and Kaufman (1956): Pile Tests, Low Sill Structure, Old River, Louisianna-Article

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Bengt H. Fellenius revisits the 1950s pile tests reported by Mansur and Kaufman for the planned Low Sill structure at Old River, Louisiana. The study was pioneering because strain measurements at multiple depths allowed researchers to estimate axial-force distributions and distinguish shaft resistance from toe resistance.<br /><br />Six instrumented piles—four closed-toe pipe piles and two H-piles—were tested in compression, with the pipe piles also tested in tension. The test site had been excavated before pile installation, creating prestressed soil conditions and effective stresses that differed from those at the project site. Fellenius notes that this history should be considered when interpreting the results.<br /><br />Reanalysis of the digitized measurements shows that residual forces left in piles after driving and loading affected both compression and tension results. Mansur and Kaufman did not account for these forces and consequently interpreted the apparent difference between tensile and compressive shaft resistance as a real difference. The reanalysis suggests that residual force inflated inferred compression resistance and produced an implausible apparent tensile resistance near the pile toe. It also highlights uncertainties in the original telltale measurements and in deriving forces by differentiating those readings.<br /><br />The article emphasizes that pile behavior should be assessed through load–movement response and acceptable foundation settlement, rather than relying only on a single defined “capacity” and an arbitrary safety factor. It also finds no evidence that adding a toe plate to an H-pile increased toe resistance; the plate may instead have reduced shaft resistance.<br /><br />Mansur and Kaufman’s work helped establish instrumented pile testing as a valuable design tool, but it did not address how isolated-pile results relate to pile groups. Group settlement depends substantially on stress distribution and soil compressibility beneath the pile toes, not just shaft interaction.

Keywords

pile tests

instrumented piles

axial force distribution

shaft resistance

toe resistance

residual force

load-movement response

foundation settlement

H-piles

pile group settlement