E.A. Dickin

Bio: E.A. Dickin is an academic researcher from University of Liverpool. The author has contributed to research in topics: Pier & Finite element method. The author has an hindex of 5, co-authored 5 publications receiving 129 citations.

Uplift response of strip anchors in cohesionless soil

Abstract: Physical and computational studies investigating the uplift response of 1m wide strip anchors in sand show that maximum resistances increase with anchor embedment ratio and sand packing. Agreement between uplift capacities from centrifuge and finite element modelling using PLAXIS, based on 0.2m computed maximum displacements, is excellent for anchors up to embedment ratios of 6. Some divergence occurs for deeper anchors. Pre-peak response is reasonably well reproduced using the Hardening Soil Model available in PLAXIS, although the characteristic post-peak softening in some physical model tests requires a more sophisticated soil model. PLAXIS also produces breakout factors which compare reasonably well with established limit state and finite element based theories.

Three-dimensional finite element studies of the moment-carrying capacity of short pier foundations in cohesionless soil

Abstract: This study is concerned with the moment-carrying capacity of short pier foundations in loose and dense cohesionless soil. The results of non-linear three-dimensional finite element analyses are compared with data from centrifuge tests modelling the behaviour of 1 m diameter prototype piers. The numerical predictions are shown to be very sensitive to the value of coefficient of earth pressure at rest, and most closely match obserbations when coefficient of earth pressure at rest = 0.6 is assumed. The results of parametric studies of square prototype piers in loose and dense cohesionless soils are then presented. Empirical equation are derived between moment-carrying capacity and pier geometry, for limiting pier rotations of 1 degree and 2 degrees, and very close fits are demonstrated between the values given by these equations and the original computed values. (A)

Numerical modelling of the load-displacement behaviour of anchor walls

Abstract: Finite element analyses of anchor wall behaviour in loose and dense sand were carried out using the variable elastic soil model and Lade's elasto-plastic soil model. The results were compared with data from centrifugal tests on models of 1 m high anchor walls. The variable elastic model, incorporating parameters derived from triaxial compression tests, yielded results which most closely matched observation. In general, the soil models considered overpredicted observed strength and stiffness, particularly for walls in dense sand.

Moment response of short rectangular piers in sand

Abstract: The moment response of rectangular piers was investigated numerically using a three-dimensional, non-linear finite element program, and by centrifuge modelling. In general numerical modelling behaviour matches observation well. Moment capacity increases almost linearly with pier length and simple expressions are derived. Dimensionless moment factors increase with soil packing but decrease significantly with pier length for aspect ratios less than 1.33. Prototype moment limits derived from the numerical and centrifuge studies compare reasonably well with predictions from the UIC/ORE and Broms design methods.

The response to uplift loading of pyramid foundations in cohesionless backfill

Abstract: The uplift behaviour of a typical pyramid-shaped foundation as used to support electricity transmission towers is investigated using the finite element package DYNA-3D. Reasonable agreement is found between uplift capacities for foundations in dense cohesionless backfill from the finite element computations and from several simplified limit state analyses. Computed soil displacements exhibit broad agreement with observed failure mechanisms around model pyramid foundations. In comparison with behaviour in centrifugal model tests at 53 gravities, computed uplift capacities are 20% higher, and computed failure displacements 40% less than predicted by physical modelling.

Lateral Resistance of Short Single Piles and Pile Groups Located Near Slopes

Abstract: Many transmission towers, high-rise buildings, and bridges are constructed near steep slopes and are supported by large-diameter piles. These structures may be subjected to large lateral loads, suc...

Sand Deformation around an Uplift Plate Anchor

Abstract: This paper presents an experimental investigation on soil deformation around uplift plate anchors in sand by using digital image correlation (DIC). The experimental setup consists of a camera, loading frame, plexiglass mold, and computer, which is developed to capture soil deformation during anchor uplifting. A series of model tests are performed to investigate the influence of particle size, soil density, and anchor embedment depth on soil deformation. A set of images captured during anchor uplifting are used to calculate soil displacement fields by DIC. The failure surface is studied by tracking the points with maximum shear strain values. On the basis of this study, it is found that soil deformation and the pullout resistance of plate anchors are substantially influenced by soil density and anchor embedment depth, whereas particle size within the studied range has limited influence. In dense sand, the shape of the failure surface changes from a truncated cone above a shallow anchor to a combine...

Uplift response of strip anchors in cohesionless soil

Abstract: Physical and computational studies investigating the uplift response of 1m wide strip anchors in sand show that maximum resistances increase with anchor embedment ratio and sand packing. Agreement between uplift capacities from centrifuge and finite element modelling using PLAXIS, based on 0.2m computed maximum displacements, is excellent for anchors up to embedment ratios of 6. Some divergence occurs for deeper anchors. Pre-peak response is reasonably well reproduced using the Hardening Soil Model available in PLAXIS, although the characteristic post-peak softening in some physical model tests requires a more sophisticated soil model. PLAXIS also produces breakout factors which compare reasonably well with established limit state and finite element based theories.

Nonlinear analysis of laterally loaded rigid piles in cohesionless soil

Abstract: In this paper, a method is developed for nonlinear analysis of laterally loaded rigid piles in cohesionless soil. The method assumes that both the ultimate soil resistance and the modulus of horizontal subgrade reaction increase linearly with depth. By considering the force and moment equilibrium, the system equations are derived for a rigid pile under a lateral eccentric load. An iteration scheme containing three main steps is then proposed to solve the system equations to obtain the response of the pile. To determine the ultimate soil resistance and the modulus of horizontal subgrade reaction required in the analysis, related expressions are selected by reviewing and assessing the existing methods. The degradation of the modulus of horizontal subgrade reaction with pile displacement at ground surface is also considered. The developed method is validated by comparing its results with those of centrifugal tests and three-dimensional finite element analysis. Applications of the developed method to laboratory model and field test piles also show good agreement between the predictions and the experimental results.

Model Studies of Bearing Capacity of Strip Footing on Sand Slope

Abstract: An experimental investigation into the ultimate bearing capacity of strip footing on sand slope is reported. The parameters investigated are the effect of setback distance of the footing to the slope crest, slope angle, relative density of sand and footing width on the ultimate bearing capacity of strip footings. A series of finite element analyses was additionally performed on a prototype slope to ascertain the validity of the findings from the laboratory model tests and to supplement the results of the model tests. The agreement between observed and computed results is found to be reasonably well in terms of load-settlement and general trend of behavior. The results show that the ultimate bearing capacity increases with increase in setback distance, relative density of sand, footing width and decrease in slope angle. At a setback distance of five times of the width of the footing, bearing capacity remains constant like that of a footing on level ground.