Applications of Suction Anchors in Offshore Technology

Abstract

The suction anchor develops a vertical breakout resistance by creating a smaller pressure beneath the anchor than the ambient pressure. The breakout behavior of model suction anchors in various soils was described. Based upon the observed failure mechanism together with the Mohr-Coulomb failure theory, a vertical breakout capacity equation for suction anchors was developed. This breakout capacity equation was presented in graphical form to facilitate computations for anchor design. Two numerical examples were given to illustrate engineering applications of the design charts.The suction anchor could be attached to offshore structures to assist withi~tallation problems and to improve stability during extreme 'events such as hurricanes. Because of their ability to increase foundation stability, suction anchors could also possibly be used to reduce the mass of. needed concrete in gravity structures, and thus reduce the cost of construction. Other potential applications of the suctionaILc~or Lnclude the anchorage of research submersibles, bottom coring platforms, and certain salvage and dredging operations. This study provides a method of assessing the value of suction-anchors by predicting anchor capacity from soil properties, anchor geometry, and suction intensity.

Formulation of uplift capacity of suction caissons using multi expression programming

“…Geotechnical centrifuge tests on model suction caissons are carried out for simulating the stress conditions and soil response at the field scale (Clukey et al, 1995;Randolph et al, 1998). Laboratory tests on model suction caissons under 1 g and controlled laboratory conditions have been conducted by some researchers (Byrne and Houlsby, 2002;ElGharbawy et al, 1999;Rao et al, 1997;Steensen-Bach, 1992;Wang et al, 1977;Whittle et al, 1998). Despite providing valuable geotechnical information, the field tests and laboratory testing of model suction caissons are quite costly, time-consuming and remain subject to various limitations.…”

Use of Suction Piles for Mooring of Mobile Offshore Bases.

“…In other research reported, Wang et al (1978) developed a general breakout capacity equation, providing a prediction method for the holding capacity of an anchor. This method used anchor geometry, suction pressure intensity, and soil properties to define breakout capacity.…”

“…Helfrich et al estimated that to achieve a 200 kN (20 metric ton) reaction force in the typical sandy soils of the continental shelf, utilizing three suction anchors having a L/D ratio of 0.65 and a factor of safety of two would result in each anchor being nearly 2 m in diameter and operated at a flow rate of about 6.4 nmVs.In the late 1970's,Wang et al (1978) made one of the early attempts to quantify breakout capacity of a suction anchor during static loading. Breakout capacity of a suction anchor was quantified by estimating the vertical soil pressure, p", required to reduce the original effective vertical pressure, a 0 ', to the effective stress at failure, o 3l \ i.e.…”

Verification of laboratory model testing and calibration of suction pile installation in sand

“…Traditional offshore structures have been composed of steel pipe piles which are driven into the deep seafloor. A substitutable way for easer pile installation process has been desired because pile driving is difficult in deep sea (Wang et al, 1978). The primary distinction between suction anchors and suction piles is that suction anchors are subject to a continuously applied suction and are usually much smaller than suction piles in size.…”