Selecting design parameters from in-situ tests to design passive piles-Paper

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The paper evaluates how to select practical input parameters for designing piles subjected to lateral soil movement, including landslides, excavation, and embankment movement. Such designs are complicated by uncertain or multiple slip depths, which may make test results difficult to apply to real sites.<br /><br />A three-layer pile–soil model is used to analyse measured responses from seven passive-pile tests across five scenarios. These include model piles and micropiles with predetermined slip surfaces, field piles under surcharge, and large anti-slide piles in a landslide with multiple slip surfaces. The model represents sliding, transition, and stable soil layers using a consistent set of parameters, including soil stiffness, stiffness contrast between layers, and limiting soil force. It can predict pile bending moments, shear forces, displacement, and soil reaction without requiring a precise slip depth for the overall maximum response.<br /><br />Predictions generally agree well with measured pile responses, including those from real-world projects with multiple slip surfaces. The analyses also show that pile-group effects and reduced thrust on rear-row piles can be accounted for. For flexible piles, predicted on-pile pressure may differ from measured earth pressure; modelling a flexible pile beneath an upper slip surface may require assuming a hinge at that depth.<br /><br />The author concludes that the selected parameters and three-layer model are sufficiently accurate for practical design of slope-stabilising piles. More detailed analysis of flexible piles’ shear-force and displacement evolution could be achieved with a bi-portion pile model.

Keywords

lateral soil movement

pile design

three-layer pile-soil model

passive piles

landslide stabilization

slip surface

soil reaction

bending moment

shear force

micropiles