The influence of foundation geometry on the uplift behaviour of piles with enlarged bases

1992 ◽  
Vol 29 (3) ◽  
pp. 498-505 ◽  
Author(s):  
E. A. Dickin ◽  
C. F. Leung
Keyword(s):  
Key Words ◽  
Design Method ◽  
Failure Mechanisms ◽  
Model Tests ◽  
Diameter Ratio ◽  
Uplift Capacity ◽  
Base Diameter ◽  
Centrifugal Model ◽  
Anchor Plates ◽  
Empirical Design

Centrifugal model tests investigating the influence of shaft to base diameter ratio and bell angle on the uplift capacity of piles with enlarged bases (or belled piers) in sand are reported. Increases in the angle of bell and in diameter ratio both result in a decrease in net uplift capacity and failure displacement. This appears to account for observed differences in uplift capacity between belled piers and anchor slabs. Studies of failure mechanisms around models of belled piers and anchor plates show distinctly different behaviour characteristics between foundation types. The comparatively low uplift capacities observed for belled piers are attributed to a lesser degree of soil mobilization. An empirical design method for belled piers is proposed in which appropriate factors which account for foundation geometry are applied to a simple continuous anchor formula. Key words : piles, sand, uplift capacity, centrifuge, design.

Centrifugal Model Tests on Vertical Anchor Plates

1983 ◽  
Vol 109 (12) ◽  
pp. 1503-1525 ◽  
Author(s):  
Edward A. Dickin ◽  
Chun F. Leung
Keyword(s):  
Model Tests ◽  
Centrifugal Model ◽  
Anchor Plates

Evaluation of the efficiencies of helical anchor plates in sand by centrifuge model tests

2012 ◽  
Vol 49 (9) ◽  
pp. 1102-1114 ◽  
Author(s):  
C.H.C. Tsuha ◽  
N. Aoki ◽  
G. Rault ◽  
L. Thorel ◽  
J. Garnier
Keyword(s):  
Soil Mass ◽  
Model Tests ◽  
Uplift Capacity ◽  
Centrifuge Model ◽  
Different Types ◽  
Loading Tests ◽  
The Individual ◽  
Helical Plate ◽  
Anchor Plates ◽  
Centrifuge Model Tests

The uplift capacity of helical anchors normally increases with the number of helical plates. The rate of capacity gain is variable, considering that the disturbance caused by the anchor installation is generally more pronounced in the soil mass above the upper plates than above the lower plates, because the upper soil layers are penetrated more times. The present investigation examines the effect of the number of helices on the performance of helical anchors in sand, based on the results of centrifuge model tests. Uplift loading tests were performed on 12 different types of piles installed in two containers of dry sand prepared with different densities. The measured fractions of the uplift capacity related to each individual helical plate of multi-helix anchors were compared with the fractions predicted by the individual bearing method. The results of this investigation indicate that in double- and triple-helix anchors, the contributions of the second and third plate to the total anchor uplift capacity decreased with the increase of sand relative density and plate diameter. In addition, these experiments demonstrated that the variation of the anchor load–displacement behavior with the number of helices also depends on these parameters.

Performance of piles with enlarged bases subject to uplift forces

1990 ◽  
Vol 27 (5) ◽  
pp. 546-556 ◽  
Author(s):  
E. A. Dickin ◽  
C. F. Leung
Keyword(s):  
Empirical Equation ◽  
Slip Surface ◽  
Surface Model ◽  
Loose Sand ◽  
Uplift Capacity ◽  
Base Diameter ◽  
Dense Sand ◽  
Centrifuge Tests ◽  
Anchor Plates ◽  
Uplift Forces

The influence of embedment, base diameter, and backfill density on the uplift behaviour of piles with enlarged bases embedded in sand was investigated in a centrifuge. Comparitive tests on straight-shafted piles are also reported. For piles in dense sand, sensible agreement was found with earlier research on anchor plates and published field data. However, uplift capacities in loose sand were considerably lower than previously observed for anchor plates. A number of theories for anchors considerably overpredict the observed capacity for belled piers in both dense and loose sand, although in the case of dense sand, reasonable values are obtained using an empirical equation derived from centrifuge tests on anchor plates and a finite element based design approach. The normally conservative vertical slip-surface model is alone in providing reasonable agreement with the surprisingly low observations for piles in loose sand. Key words: piles, uplift capacity, centrifuge tests, sand.

scholarly journals A Comparison between the Empirical and Mechanistic-Empirical Pavement Design Methods

2019 ◽  
Vol 7 (07) ◽  
Author(s):  
Dr. Mohammed Shallal ◽  
Elsir Suliman Ahmed
Keyword(s):  
Comparative Study ◽  
Key Words ◽  
Design Method ◽  
Design Methods ◽  
Pavement Design ◽  
Empirical Methods ◽  
Traffic Loading ◽  
Aashto 1993 ◽  
Empirical Design ◽  
Subgrade Strength

In this paper a comparative study has been carried out between the Mechanistic-Empirical Pavement Design Methods and the Empirical Pavement Design Methods. For the purpose of this paper, nine pavement design sections have been prepared using the Mechanistic-Empirical Methods represented by the Asphalt Institute Design Method (SW-1 software of the Asphalt Institute) and the Empirical Design represented by AASHTO 1993 and TRL Road Note No.31, using the same traffic loading and subgrade strength. Three traffic loading scenarios have been considered for this study. (Key words: Mechanistic-Empirical, Empirical, axle loads, Subgrade Strength, pavement design)

Factored axial compressive resistance of schifflerized angles

1991 ◽  
Vol 18 (6) ◽  
pp. 926-932 ◽  
Author(s):  
Seshu Madhava Rao Adluri ◽  
Murty K. S. Madugula
Keyword(s):  
Key Words ◽  
Design Method ◽  
Design Criteria ◽  
Design Practice ◽  
Buckling Mode ◽  
Flexural Buckling ◽  
Mode Of Failure ◽  
Current Design ◽  
Similarities And Differences ◽  
Compressive Resistance

The concept of schifflerization of 90° equal-leg angle is presented and its application in triangular-base latticed steel towers is explained. The similarities and differences between schifflerized angles and regular 90° angles are discussed. The current design practice for schifflerized angles is reviewed and its limitation is highlighted. A design method which includes the effect of the torsional-flexural buckling mode of failure is proposed. For ready use of designers, the factored axial compressive resistances of schifflerized angles are tabulated for both the present and proposed design methods. Key words: buckling, compressive resistance, design criteria, schifflerized angles, stability, standards, steel, struts, towers, guyed towers.

Development of a Multifactor Regression Model of Ship Maneuvering Forces Based on Optimized Captive-Model Tests

2006 ◽  
Vol 50 (04) ◽  
pp. 311-333 ◽  
Author(s):  
S. Sutulo ◽  
C. Guedes Soares
Keyword(s):  
Experimental Design ◽  
Polynomial Regression ◽  
Design Method ◽  
Model Tests ◽  
Ship Maneuvering ◽  
Captive Model Tests ◽  
Experimental Design Method ◽  
Force Moment ◽  
Force Components ◽  
Multifactor Regression

The paper provides the results of model tests planned with an optimized experimental design method. Captive-model tests have been carried out according to such a design on a computerized planar-motion carriage with a model of a fast catamaran with five varying factors (drift angle, rate-of-yaw amplitude, sinkage, trim and heel angles) and with all six force/moment components measured at each run. The measured values were used after preprocessing for construction of polynomial regression models for all force components acting upon the catamaran's hulls. It is demonstrated that the optimized experimental design method allows rather complicated mathematical models for maneuvering hydrodynamics forces to be obtained from captive model tests at a reasonable level of effort.

Uplift Capacity of Anchor Plates in Two-layered Cohesive-frictional Soils

2011 ◽  
Vol 11 (3) ◽  
pp. 589-591 ◽  
Author(s):  
Hamed Niroumand ◽  
Khairul Anuar Kassim ◽  
Ramli Nazir
Keyword(s):  
Uplift Capacity ◽  
Anchor Plates ◽  
Frictional Soils
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