An analytical approach for the prediction of single pile and pile group behaviour in clay

Abstract

In this paper, the 't-z method' is employed to describe the nonlinear behaviour of a single pile and is used to obtain simplified predictions of pile group behaviour by considering the interaction between two-piles in conjunction with the Interaction Factor Method (IFM). The principal inconvenience of the t-z method arises from the determination of the resisting curve's shape; an improvement upon this aspect is the main aim of this study. Partial slip is considered using a new analytical approach which is an adaptation of a model based on bond degradation. Pile installation effects and interface strength reduction are uncoupled and considered explicitly in this study. Lateral profiles of mean effective stress after pile installation and subsequent consolidation which were representative of predictions determined in a previous study using a modified version of the cavity expansion method (CEM) are adopted; these predictions are subsequently used to relate installation effects to changes in soil strength and stiffness. In addition, the 'reinforcing' effects of a second, 'receiver', pile on the free-field soil settlement is considered using a nonlinear iterative approach where the relative pile-soil settlement along the pile shaft is related to the soil spring stiffness. Through comparisons with previously published field test data and numerical simulations, the results indicate that the proposed approach provides a sufficiently accurate representation of pile behaviour while conserving considerable computing requirements.

EXPERIMENTAL FIELD investigations OF DEFORMABILITY of claystones and sandstones

“…исследованием работы свайных фундаментов на глинистых грунтах в различные годы занимались многие отечественные и зарубежные ученые [9][10][11][12][13][14][15][16][17][18][19][20][21][22][23][24]. of 0.6…2.2 MPa, which is characteristic of less stable varieties of claystones and sandstones.…”

“…It is rational to use in calculations of foundations on claystones and sandstones the values of the strength parameters of the soil obtained in laboratory or field tests with soaking, taking into account the possible deterioration of the properties of these soils. было доказано, что работа фундаментов на аргиллитоподобных глинах и песчаниках существенно отличается от работы свайных фундаментов на современных глинах и песках, не обладающих цементационными связями [11,12,23,24]. анализ осадки свайных фундаментов, опирающихся на современные твердые глины и аргиллитоподобные глины, выполненный в работе [11], показал, что для аргиллитоподобных глин свойственны упругие деформации, которые составляют 46…69 % от общих деформаций.…”

Semi-analytical approach for time-dependent load–settlement response of a jacked pile in clay strata

“…There are two analytical approaches available for evaluating the changes in stress state caused by pile installation: the strain path method (SPM) and the cavity expansion method (CEM). Compared with the SPM, although the CEM is a one-dimensional approach, it has the advantage that a closed-form solution is likely to model the stress changes during pile installation, which facilitates the analysis procedure for the subsequent consolidation (Sheil and McCabe 2016). Moreover, many previous studies demonstrated that the cavity expansion theory can evaluate the stress state of the surrounding soil with sufficient accuracy (Guo 2000;Randolph 2003).…”

“…Generally, the function for the t-z curve can be determined by either empirical approach or theoretical D r a f t analysis (Zhu and Chang 2002). Over the past few decades, the load-transfer method has been greatly improved by incorporating the soil stress history, the nonlinear soil behaviour, and the pile installation effects, etc., into the t-z curve (e.g., Ashour et al 2010; Roberts and Misra 2009;Nanda and Patra 2014;Sheil and McCabe 2016) Recently, Wang et al (2012) further developed a load-transfer method by considering the elastic response of the soil outside the pile-soil interface. However, the evolution of the mechanical behaviour of the surrounding soil has not yet been incorporated into the t-z curve to consider the time-dependent pile-soil interaction behaviour.…”

Improved Soil-Pile Interaction of Floating Pile in Sand With Shaft Treatment

“…The entire soil-pile system can be simulated and analysed with Finite Element or Boundary Element Methods, as can be found in works by Padron et al [6], Wang et al [7] and Sheil, et al [8], among others. These analytical works mainly revolve around the assumed premise of the soil-pile system as one composite continuum, taking into consideration complex influencing factors, such as pile-soil-pile interaction, 3D pile group configurations and soil anisotropy [9].…”