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

Abstract

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 described. Uplift capacity is strongly influenced by anchor diameter, embedment ratio, and sand density. In tests on shallow half-cut models, a gently curved rupture surface emerged from the top edge of the anchor to the sand surface at approximately ϕ/2 to the vertical, where ϕ is the angle of shearing resistance. For a deep anchor, a balloon-shaped rupture surface emerged at 0.8ϕ to the vertical immediately above the anchor and was confined within the sand bed. The load-displacement behaviour of full-shaped models was three-phase and two-phase for shallow and deep anchors, respectively. Alternative methods of determining the critical embedment ratio are considered, and values of 4.8, 5.9, and 6.8 are proposed for loose, medium-dense, and dense sand, respectively. Empirical equations are presented which yield breakout factors similar to those from many published laboratory and field studies.Key words: circular anchor, uplift capacity, sand, critical embedment ratio, failure mechanism.

Three-dimensional lower-bound solutions for the stability of plate anchors in sand

“…This may in part explain the discrepancy between the numerical lower bounds and Pearce's results at larger embedment ratios. Also shown in (Figure 9(b)) are the chamber test results of Ilamparuthi, Dickin and Muthukrisnaiah (2002). These chamber tests results compare more favourably to the numerical results than those of Pearce (2000).…”

Helical piles: an innovative foundation design option for offshore wind turbines

“…There will also be some contribution from the shaft friction below the bottom plate and (for compression) a contribution from end bearing on the pile. A considerable amount of work is available to aid development of design approaches (for example, uplift plate factors from Merifield [12] or Llamparuthi et al [13]), and standard calculation approaches from the American Petroleum Institute or Det Norske Veritas pile design methods may also be applicable [14,15]. For pullout in undrained soils, there needs to be a careful consideration of the response at the base of the pile, particularly if the water depths are sufficiently shallow that cavitation may occur.…”

Pullout resistance of single vertical shallow helical and plate anchors in sand

“…3) for plate anchors were deduced by trials and error from Eq. 33 using the pullout capacity results of Ilamparuthi et al (2002). The different values of this constant for plate anchors were also given in Fig.…”

“…Meyerhof and Adams (1968) proposed a value for the base angle (h 1 ) of the failure plane with the vertical in the range of u/4-u/2. While a value of u/2 has been proposed by Clemence and Veesaert (1977), Murray and Geddes (1987), and Ilamparuthi et al (2002). Based on the experimental results, Ghaly et al (1991) suggested a value for the angle h 1 as 2u/ 3 for shallow anchors.…”

“…Ghaly and Hanna (1994b) developed theoretical models to predict the pullout capacity of single vertical anchors installed into shallow, transition, and deep depths using the limit equilibrium technique together with Kotter's differential equation to calculate the shear stresses acting on the log-spiral surface. Recently, Dickin and Leung (1990) and Ilamparuthi et al (2002) have presented a thorough review of the design theories for anchors available in the literature. Trofimenkov and Mariupolskii (1965) and Healy (1971) proposed a critical depth/diameter ratio of approximately 6 to identify shallow anchors.…”