Abstract
A set of simple finite-element modelling procedures that can be used to estimate the load–settlement behaviour of continuous helical displacement (CHD) piles in sand is presented. The approach makes use of a stress- and strain-dependent non-linear soil model that can be parameterised using basic soil data that can be determined through routine site investigation. The procedures are validated against a database of physical model tests (reported in a companion paper), where they are shown to be suitable for estimating the load–settlement behaviour of CHD piles within the serviceability range. In this way they are complementary to the analytical method reported in the companion paper for estimating the ultimate capacity of a CHD pile. In this paper, the finite-element method and analytical model are applied to four historical load tests on CHD piles conducted at three different sand sites. The modelling is further validated and used to discuss potential savings in pile material and therefore cost due to additional confidence in performance determination at both ultimate and serviceability limit states.
Highlights
IntroductionThe authors’ companion paper (Jeffrey et al, 2016) described the continuous helical displacement (CHD) pile type and
The authors’ companion paper (Jeffrey et al, 2016) described the continuous helical displacement (CHD) pile type andDownloaded4b3y6[] on [15/02/22]
This was approximated in the finite-element modelling (FEM) simulations by subdividing the soil mesh close to the pile into four equal-length vertical clusters within each diameter band (Figure 6), within which a single set of constitutive parameters was assumed to apply, determined according to the average post-installation relative density inferred in that zone, as described in the companion paper
Summary
The authors’ companion paper (Jeffrey et al, 2016) described the continuous helical displacement (CHD) pile type and. Based on a database of test data derived from model pile installation and load testing in sands across a wide range of relative densities, the companion paper developed values of the bearing capacity factor (Nq) and lateral earth pressure coefficient (K ) for use in standard analytical approaches for design at the ultimate limiting state. Following validation against the model tests, the FEM (and the analytical capacity method) are subsequently applied to the prediction of a series of pile load tests from three different field sites around the UK, extracted from a larger database for CHD piles in a range of soil types developed by Roger Bullivant Ltd, UK. It will be shown that the use of the analytical method and FEM can allow designers to produce more efficient CHD pile designs in sands (i.e. confidently utilise a larger proportion of the available capacity and thereby reduce required pile lengths)
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