1,326 research outputs found
Exact Winkler solution for laterally loaded piles in inhomogeneous soil
No full textA novel exact analytical solution is derived for the equation y(4)+xny=0 in the region x≥0, which is important for the analysis of piles in soil with stiffness varying with depth. To date, exact solutions for long piles are available only for the cases where n=−4, 0, and 1. For other values of the exponent n, solutions have formerly been obtained numerically, mainly by the finite-difference method or approximate analytical solutions. An inherent difficulty in obtaining solutions for long beams (which are used to model flexible piles) lies in the inability to isolate the regular, converging part of the solution over the singular part that diverges with increasing x. In this paper, an exact solution is derived for n>−4, focusing on the important case of semi-infinite beams. Key aspects of the problem such as the stiffness and flexibility matrices at the pile head, and the peak bending moments due to eccentrically acting lateral loads, are discussed. A novel approach for deriving Winkler spring moduli for combined force and moment loading is proposed and shown to provide good agreement with rigorous numerical continuum results
CRISPIN GLOVER
No full textIn public discourse, Crispin Glover is orientated to the reader/viewer via mainstream Hollywood, but as that fabricated exchange with a subcultural online star illustrates, this too occurs through cult discourse. The quality and box-office success of the mainstream work and how it utilises the cult screen personality of ‘Crispin Glover’ declines as his personal pursuit of surrealist projects increases. The intensity and acute characterisation of Glover’s acting remains key to the actor’s cult status, negating the very mainstream work he has undertaken. Glover uses the term ‘corporate’ when talking about the mainstream Hollywood industry and modes of production, distribution and exhibition. The juxtaposition of Glover’s cult, offbeat identity with his firm control over all elements of production suggests almost a cult parody of the classical mogul. The majority of Glover’s responses to questions across his interviews are remarkably similar, often literally word-for-word
Theoretical “t-z” Curves for Piles in Radially Inhomogeneous Soil
No full textAccurate estimates of pile settlement are key for efficient design of axially loaded piles. Calculations of pile settlement can be simplified using one-dimensional “t-z” curves describing pile settlement at a certain depth as a function of side friction. In the realm of this simplified framework, theoretical “t-z” curves can be derived by substituting an attenuation function describing the variation of shear stress with distance from the pile, into a soil constitutive model relating shear strain to shear stress, then integrating with respect to distance to get the settlement at the pile circumference due to an applied shear stress. A handful of analytical “t-z” curves are available in the literature using the concentric cylinder model to define an attenuation function; these include solutions for linear-elastic, power-law and hyperbolic constitutive models. However, radially homogeneous soil has often been assumed, ignoring the effect of the pile installation resulting in unconservative calculations of pile settlement. This paper considers the installation of the pile, resulting in a radially variable shear modulus distribution in the surrounding soil. A radial inhomogeneity correction factor has been developed for selected constitutive models based on two simplified functions for the soil inhomogeneity, which can be applied to the previously derived “t-z” curves produced assuming radially homogeneous soil. The performance of this simplified method is investigated
Settlement of axially loaded pile groups in inhomogeneous soil
No full textAccurate prediction of settlement is key to performance-based design of pile groups. Simple methods based on physically motivated modelling assumptions, in conjunction with wisely chosen soil material constants, can accurately predict settlements without having to perform complex numerical analysis in three dimensions. Interaction factors, introduced by Poulos, simplify the analysis of pile groups through superposition of the effects of only two piles at a time. Closed-form solutions for interaction factors between piles in homogeneous soils are available in the literature, incorporating both the displacement field around a single pile and the reinforcing effect of a second pile. This paper will investigate pile groups embedded in inhomogeneous soils with shear modulus varying with a power law function of depth. The problem is formulated by considering the response of a ‘receiver’ pile carrying no load at its head, subjected to the displacement field of a loaded ‘source’ pile. A simplified approximate expression is developed using a model error correction factor that is suitable for routine design use. The performance of the proposed model at predicting experimental results is investigated. Dimensionless design charts and an illustrative example are provided
A simplified analytical model for developing “t-z” curves for axially loaded piles
No full textPile settlement estimation can be simplified using one-dimensional “t-z” curves to describe the relationship between shear stress and settlement at the pile-soil interface at a specific depth. This simplifies the two-dimensional continuum problem to that of a one-dimensional rod. Some analytical “t-z” curves are available in literature; however, to employ these solutions a suitable soil constitutive model, expressed in a flexibility form γ = γ(τ), must be chosen. This must be carefully calibrated against laboratory test data to accurately represent soil behaviour. This paper explores an alternative approach for piles in clay employing a direct similarity-based relationship between a shear stress-strain curve and a “t-z” curve. A linear-transformation factor is derived which can be applied to a representative soil test directly from the site to produce a “t-z” curve, thus removing the need to calibrate/integrate a suitable soil constitutive model. Suitable values for this factor have been obtained through comparison with existing analytical “t-z” curves
Simplified models for axial static and dynamic analysis of pile foundations
No full textIn this chapter, simplified methods for static and dynamic analysis of pile foundations under axial loads are discussed. Firstly, a number of analytical solutions for Winkler springs and dashpots are briefly reviewed. Secondly, exact and approximate solutions for stiffness of single piles are derived for both homogeneous and inhomogeneous soil profiles using the Winkler model. The approximate solutions are based on energy principles obtained my means of shape functions analogous to those used in finite-element formulations. Thirdly, solutions for grouped piles are derived using the superposition approach of Poulos and Davis. To this end, a family of interaction factors accounting for pile-soil-pile interaction is reviewed. It is shown that soil inhomogeneity and pile-to-pile interaction may have a profound impact on pile head stiffness and ensuing settlement. Results are presented in the form of dimensionless graphs and charts that elucidate critical aspects of the problem, and detailed comparisons with more rigorous numerical continuum solutions are provided. Application examples are presented and discussed
First person – Jamie Whitelaw
No full textFirst Person is a series of interviews with the first authors of a selection of papers published in Journal of Cell Science, helping researchers promote themselves alongside their papers. Jamie Whitelaw is first author on ‘ CYRI-B loss promotes enlarged mature focal adhesions and restricts microtubule and ERC1 access to the cell leading edge’, published in JCS. Jamie conducted the research described in this article while a post-doctoral researcher in Prof. Laura Machesky's lab at CRUK Scotland Institute, Glasgow, UK. He is now a Lecturer at University of the West of Scotland, Blantyre, investigating host–pathogen interactions with a focus on the role of the host cytoskeleton
Kathleen Jamie, Chitra Ramaswamy & Amanda Thomson: Antlers of Water - Live Event
No full text‘When we read and write, when we love our fellow creatures, when we walk on the beach, when we just listen and notice, we are not little cogs in the machine, but part of the remedy.’ These luminous words by Kathleen Jamie form part of the introduction to Antlers of Water, an outstanding collection of contemporary Scottish writing about nature and landscape.
The generosity of Jamie’s approach as editor of the collection goes beyond the stellar selection of contributors such as Amy Liptrot, Karine Polwart and Malachy Tallack: she also invokes the agency of readers to make a difference. ‘If, by reading, you are encouraged or confirmed in your love of the natural world, if you’re inspired simply to… look outside, then our job is done.’
In a discussion led by the BBC's Clare English, Jamie is joined by award-winning journalist Chitra Ramaswamy as well as visual artist and writer Amanda Thomson – both contributors to the anthology – to discuss Scotland, landscape and the more-than-human world around us.
This is a live event, with an author Q&A.
Part of the Edinburgh International Book Festival Making Climate Change Personal festival theme
Analytical non-linear "m-θ" curves for monopiles in clay
No full textDependable predictions of monopile foundation response to lateral loads is crucial to the efficient design of offshore wind turbine foundations. For squat monopile foundations, it is important to incorporate the distributed non-linear moment-rotation response with depth, known as “m-θ” curves, in addition to traditional “p-y” curves and lumped force-displacement curves at the pile base. Recognising the limited number of “m-θ” curves available in the literature, this paper develops new theoretical “m-θ” curves using a rational two-dimensional horizontal pile/soil “slice” model to obtain improved representations of the stress and displacement fields in the soil around the pile. Firstly, this model undergoes validation through comparisons with available linear-elastic solutions. Subsequently, it is employed in conjunction with a numerical discretisation of the pile circumference to obtain non-linear “m-θ” curves accounting for both soil yielding and slippage between pile and soil. The resulting curves are compa
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