Performance of Helical and Square Plate Anchors in Cohesionless Soil

2021 ◽  
pp. 741-751
Author(s):  
A. I. Dhatrak ◽  
L. S. Amrutkar ◽  
S. W. Thakare ◽  
R. R. Badnakhe
1989 ◽  
Vol 29 (3) ◽  
pp. 138-144 ◽  
Author(s):  
Braja M. Das ◽  
Vijay K. Puri
Keyword(s):  

Author(s):  
Nabil Al Hakeem ◽  
Charles Aubeny

Plate anchors are among the most effective anchorage systems that are widely used to resist horizontal and inclined uplift loads in many offshore and onshore applications. Previous research on plate anchors has largely focused on the horizontal or vertical breakout problems, with limited attention directed towards obtaining a full characterization of the effects of anchor orientation angle. The present study utilizes displacement-based finite element analyses to investigate the stability and performance of strip anchor embedded in cohesionless soil for plate inclination angles ranging from 0o to 90o from horizontal, where the applied load is normal to and acts at the center of the plate. This study investigates the effects of scale and roughness, along with the geometry of the failure mechanism for various plate orientations and embedment depths. The analyses, presented in terms of a non-dimensional breakout factor Nq, show that the breakout factor increases significantly with an increase in the inclination, especially for angles greater than 45 degrees in loose sand and greater than 60 in dense sand. The analyses also show that scale effects (anchor width) can affect capacity. Finite element analyses have been used to introduce simple design charts relating the breakout factor to the embedment depth and relative density. Comparisons to experimental and numerical studies showed good agreement.


2020 ◽  
Vol 2020 ◽  
pp. 1-10
Author(s):  
Tugen Feng ◽  
Jingyao Zong ◽  
Wei Jiang ◽  
Jian Zhang ◽  
Jian Song

Three-dimensional nonlinear numerical analysis is carried out to determine the ultimate pullout capacity of a square plate anchor in layered clay using the large finite element analysis software ABAQUS. An empirical formula for the pullout bearing capacity coefficient of a plate anchor in layered soils is proposed based on the bearing characteristics of plate anchors in single-layer soils. The results show that a circular flow (circulation field) is induced around the plate anchor during the uplift process and that the flow velocity and circulation field range are mainly affected by the properties of the soil around the plate anchor. The bearing characteristics of plate anchors in layered soils are influenced by factors such as the embedment depth of the plate anchor, the friction coefficient between the soil and the plate anchor, the thickness of the upper soil layer, and the thickness of the middle soil layer. The rationality of the finite element numerical calculation results and the empirical formula is verified by comparing the results from this study with results previously reported in the literature.


2011 ◽  
Vol 250-253 ◽  
pp. 1469-1473
Author(s):  
Xin Zhang ◽  
Jin Chao Yue

Plate anchor is one of the most popular types of anchors widely used in geotechnical engineering. Reliable prediction of the ultimate uplift resistance of plate anchors requires its failure modes well understood. In this paper, an image-based deformation technique, the digital image cross-correlation (DIC), is used to measure the sand deformations around a scaled semi-circular anchor during uplifting. A series of tests have been conducted to investigate the failure modes of plate anchors in both loose and dense sand. Two distinctively different failure modes are measured by using DIC in both loose and dense sand respectively. This model study improves the understanding of the failure and development of loading capacity of uplift anchor in cohesionless soil.


Author(s):  
Nabil Al Hakeem ◽  
Charles Aubeny

Vertically driven plate anchors offer an attractive anchoring solution for floating offshore structures, as they are both highly efficient and suitable for a wide range of soil conditions. Since they are oriented vertically after installation, keying is required to orient the anchor into the direction of applied loading. Simulation of the keying process has not been extensively investigated by previous research, especially for cohesionless soil. Reliable prediction of irrecoverable embedment loss during keying is needed, since such loss can lead to significant reduction in the uplift capacity of the plate anchors. Large deformation finite element analyses LDFE method using RITSS (Remeshing and Interpolation Technique with Small Strain) were used to simulate the keying process of strip plate anchor embedded in uniform cohesionless soil. LDFE showed that the loss in embedment depth of plate anchor during rotation is inversely proportional to the loading eccentricity e/B. It was also found that the maximum pullout capacity occurs before the end of keying process at orientations between 60° to 85° degrees for vertical loading. Also, the LDFE study showed that reduced elastic soil stiffness leading to increased levels of displacement at which the peak load is approached.


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