Residual Force. Revisiting Hunter and Davisson (1969)-Video

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Video Summary

Henrik Christensen filled in for Bengt, who was recovering from a serious car accident, to revisit a 1969 paper on residual loads in piles. Residual load develops after pile installation and before testing, as the pile and surrounding soil reach equilibrium. Ignoring it can distort estimates of shaft resistance and end bearing, affect predicted pile stiffness, and change the calculated ultimate resistance.<br /><br />The paper examined load tests on piles installed near the Mississippi River, including compression and tension tests with strain measurements. Christensen reviewed Bengt’s reinterpretation of the results using current design concepts, including a beta-method shaft-resistance profile. The analysis suggested similar shaft resistance in tension and compression, and comparable load–movement behavior for impact- and vibratory-driven piles, while jetted piles behaved differently.<br /><br />During discussion, Christensen explained that the revised curves were developed using a beta value of 0.3 and an assumed end-bearing value.

Keywords

residual loads

pile load tests

shaft resistance

end bearing

pile stiffness

beta method