During the last 30 years various researchers have proposed approximate techniques to estimate the uplift capacity of soil anchors. As the majority of past research has been experimentally based, much current design practice is based on empiricism. Somewhat surprisingly, very few numerical analyses have been performed to determine the ultimate pullout loads of anchors. This paper presents the results of a rigorous numerical study to estimate the ultimate pullout load for vertical and horizontal plate anchors in frictional soils. Rigorous bounds have been obtained using two numerical procedures that are based on finite element formulations of the upper and lower bound theorems of limit analysis. For comparison purposes, numerical estimates of the break-out factor have also been obtained using the more conventional displacement finite element method. Results are presented in the familiar form of break-out factors based on various soil strength profiles and geometries and are compared with existing numerical ...

The ultimate pullout capacity of anchors in frictional soils

An experimental investigation of the uplift behaviour of relatively large scale model circular plate anchors up to 400 mm in diameter embedded in loose, medium-dense, and dense dry sand is describe...

Experimental investigation of the uplift behaviour of circular plate anchors embedded in sand

Helical piles are increasingly used to support and rehabilitate structures subjected to both tensile and compressive axial loads This paper presents a detailed investigation into the axial perform

Axial testing and numerical modeling of square shaft helical piles under compressive and tensile loading

The design of buried anchors and pipelines requires assessment of the peak uplift resistance. This paper describes a limit equilibrium solution for the uplift resistance of pipes and plate anchors buried in sand. The geometry of this solution reflects observations from model tests. Peak angles of friction and dilation are found using established correlations that capture the influence of stress level and density. These angles govern the geometry of the failure mechanism and the mobilised resistance. The solution is validated using a database of 115 model tests on pipes and strip anchors assembled from the published literature. Good agreement with the overall database is shown, without optimisation of any input parameters. The method overpredicts the uplift resistance of smooth model pipes by ∼10%, highlighting the influence of pipe roughness. In contrast, it is shown that the solution for uplift resistance based on the limit theorems of plasticity is generally unconservative. The assumption of normality, ...

The uplift resistance of pipes and plate anchors buried in sand.

The soil–pipeline interactions in sand under lateral and upward movements are investigated with particular attention to the peak forces exerted on the pipe. The analytical solutions for estimating the peak forces are summarized and it is shown that, for deep embedment condition, there is large uncertainty in the true values since the bounds established by the analytical solutions are large. In order to find the solution for the peak force and to investigate its transition from shallow to deep failure mechanism, finite element analyses of lateral and upward pipe movements are performed for different embedment conditions. Two different soil models (Mohr–Coulomb and Nor–Sand models) are used for the simulations. The accuracy of the analysis is first examined by simulating experimental tank tests. The analysis is further extended to deeper embedment ratios of as large as 100. The obtained finite element results are used to construct a design chart for deep embedded pipelines.

Lateral and Upward Soil-Pipeline Interactions in Sand for Deep Embedment Conditions

An investigation into the vertical uplift of anchor plates in a cohesionless medium is described. Factors investigated in relation to the loaddisplacement response were the size and shape of plate,...

Uplift of Anchor Plates in Sand

Results are presented of model-scale vertical pulling tests carried out on groups of square anchor plates in row and square configurations. The tests were carried out at a single depth of embedment, which ensured shallow anchor behavior in the sand placed at a constant dry density. It is shown that the load-displacement relationships for all groups may be reduced to a common curve. The load-carrying capacity of a group of anchor plates increases with the spacing between the individual plates up to a limiting critical value, and it is demonstrated how the results of pulling tests with different numbers of plates in a group may be described in a simple unifying manner. A possible means of predicting the effect of interaction on the uplift capacity of both modeland full-scale anchors in row configurations is suggested. For laboratory tests on a linear group of five anchors, it is shown that the end anchors attain the highest loads but all loads converge to an equal value as the spacing increases to the criti...

Plate Anchor Groups Pulled Vertically in Sand

There are various forms of soil anchor that rely on passive resistance and/or skin friction to resist inclined tension loads arising from their use as structural components. This note outlines the observed behavior of deep passive plate anchors in laboratory tension tests. The results for plates of various shapes pulled at angles between the vertical and the horizontal through a cohesionless medium are presented. Previous published information has mainly been concerned with the vertical uplift of anchors or with the resistance of anchors to horizontal loads. There is far less information available on inclined anchors. The laboratory data, which forms part of a larger study of anchor behavior, is briefly compared with the experimental results on inclined circular ball anchors of Larnach and data from Meyerhof.

Edward J. Murray

Papers

Uplift of Anchor Plates in Sand

Plate Anchor Groups Pulled Vertically in Sand

Passive inclined anchorages in sand

Closure to “Plate Anchor Groups Pulled Vertically in Sand” by James D. Geddes and Edward J. Murray