Performance of Laterally Loaded Helical Piles in Clayey Soils Established From Field Experience-Article

Article

Pdf Summary

The study reports 14 full-scale lateral load tests at five sites in Alberta and Manitoba, comparing helical and driven piles in soils ranging from very soft clay to very hard clay till. Tested pile shafts were 219–508 mm in diameter. The research examined pile diameter, embedment, installation effects, and the ability of LPILE 2016 to predict lateral response.<br /><br />All piles resisted substantial lateral loads, with nonlinear load–deflection behavior. Shaft diameter was the main influence on lateral resistance: larger shafts generally carried greater loads. In contrast, increasing embedment had relatively little effect once piles extended below the soil zone actively involved in resisting lateral movement. Helical and driven piles with equal shaft diameters showed similar responses, even though the driven piles at one site were embedded more deeply.<br /><br />Installation-related soil disturbance could significantly reduce resistance, particularly in soft clay and where predrilling was used. Smaller augers reduced this effect. The study also found that creep under sustained lateral loading can be considerable in cohesive soils, especially at high loads.<br /><br />LPILE predictions generally agreed reasonably with measurements at low deflections, but accuracy was less reliable at larger movements and where installation disturbed the soil. Adjusting the model with a displacement (“y”) multiplier helped represent disturbance. Overall, the findings indicate that helical piles can provide substantial lateral capacity, and that shaft size and upper-layer soil conditions are more influential than total pile length.

Keywords

helical piles

driven piles

lateral load tests

lateral resistance

pile diameter

embedment depth

soil disturbance

soft clay

creep behavior

LPILE 2016