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Centrifuge tests investigating the effect of suction caisson installation in dense sand on the state of the soil plug
Published in Andrew McNamara, Sam Divall, Richard Goodey, Neil Taylor, Sarah Stallebrass, Jignasha Panchal, Physical Modelling in Geotechnics, 2018
M. Stapelfeldt, B. Bienen, J. Grabe
A suction caisson is installed in two stages: The self-weight penetration and the suction installation. In the first stage, the caisson is lowered to the mud line and the skirt penetrates into the seabed due to the self-weight of the caisson and the wind turbine substructure. The actual penetration depth results from the submerged self-weight of the structure and the bearing capacity of the skirt tip; mainly depending on the wall thickness and the in situ soil characteristics (e.g. Tran et al. 2004, Houlsby & Byrne 2005 and Andersen et al. 2008). When an equilibrium is reached, the self-weight penetration is completed and the suction installation can commence. Water trapped inside the caisson is pumped out and a differential pressure to ambient (i. e. suction) is created, which results in seepage flow around the skirt into the caisson. Consequently, the effective stresses inside the caisson and at the skirt tip are reduced. The combination of suction pressure, seepage flow and self-weight, enables the installation of a caisson foundation – even in dense or very dense sand (e.g. Tjelta 1995, Houlsby & Byrne 2005 and Bienen et al. 2018).
Model tests on performance of offshore wind turbine with suction caisson foundation in sand
Published in Marine Georesources & Geotechnology, 2020
Hai-lei Kou, Dan-liang Yang, Wang-chun Zhang, Yi-fan Wu, Qiang Fu
Suction caisson are large, hollow, cylindrical steel or concrete structures in form of upturned bucket shape (Wang, Demars, and Nacci 1978; Andersen and Jostad 1999; Houlsby and Byrne 2005; Randolph et al. 2011; Shahr-Babak, Khanjani, and Qaderi 2016; Skau et al. 2019). The earliest concept of using suction caisson was introduced in the literature in 1958 (Mackereth, 1958). Suction caissons are penetrated into the seafloor bottom sediments by self-weight or suction. The principle of the suction caisson technique is to apply a suction pressure inside the sealed cylindrical caisson to create a downward net force to sink the caisson into the seabed. The suction pressure is removed after the suction caisson has been installed to the designed depth. Therefore, they were widely used as mooring anchors (Zhang, Zhang, and Lu 2007), foundations for offshore platforms (Zhang and Ding, 2011) and wind turbines (Houlsby and Byrne, 2000; Byrne et al. 2002; Houlsby, Kelly, and Byrne 2005; Gavin, Igoe, and Doherty 2011), and breakwaters or seawalls (Takahashi, Tanimoto, and Shimosaka 1994; Chu, Yan, and Li 2012).
A coupled CFD-DEM simulation of upward seepage flow in coarse sands
Published in Marine Georesources & Geotechnology, 2019
Zhe Ma, Yin Wang, Nianxin Ren, Wei Shi
With the development of technology, offshore oil and gas industry is going to deeper water with floating platform. The floating platform was connected to seabed using mooring line and anchor system. Conventional driven piles may be used as anchors in seabed but have to suffer from several disadvantages, such as low efficiency, high cost and difficult operation in deep water. For seabed of clayed and sandy soil stratigraphy, suction anchors or suction caissons are widely used nowadays (Byrne and Houlsby 2003; Houlsby and Byrne 2005). They are quicker to install and easy to remove compared to conventional driven piles. Suction anchor is an upturned bucket of cylindrical shape with thin walls made from steel. In the field, the suction caisson is first lowered into the seabed under its self-weight; after reaching a target depth, which is large enough to guarantee the seal formed between the soil and the caisson wall, a kind of “suction” or “negative pressure” is applied by pumping out the entrapped water in the caisson cavity. This negative pressure helps penetrate the suction caisson into the seabed further (Andersen, Jostad, and Dyvik 2008; Senders and Randolph 2009).
Failure mode and capacity of suction caisson under inclined short-term static and one-way cyclic loadings
Published in Marine Georesources & Geotechnology, 2018
Zhen Guo, Dong-Sheng Jeng, Wei Guo, Lizhong Wang
In the past few decades, suction caisson has been increasingly used as an effective solution for anchoring in deep water (Randolph et al. 2005; Randolph et al. 2011). Suction caisson is a large, steel-made, and thin-walled structure, which is open at the bottom and closed at the top. Compared with traditional pile and drag-embedded anchor, the suction caisson has several significant advantages including its easy handling of the field installation, accurate positioning, greater pullout capacity, and adaptability for complicated loading conditions.