Appropriate estimating bearing capacity of bucket foundations embedded in two-layered soil is a significant subject in geotechnical engineering. The effects of embedment on the ultimate bearing capacity of wide-shallow bucket foundations (WSBFs) in two-layered clay were analysed. A parametric study was performed for the relative thickness of the upper soil, the relative soil strength, and the depth-diameter ratio of the foundation. The finite element (FE) results were presented in terms of the modified bearing capacity factor that reflects the influence of parameters mentioned above. Different types of failure mechanisms were described as the above-mentioned parameters changed.
As an environmentally friendly energy, wind energy has the characteristics of sustainable regeneration and inexhaustibility, so that the use of wind turbines to generate electricity is becoming increasingly common. The offshore wind has huge energy value because it is faster and more stable. However, installation cost and engineering complexity of offshore wind turbines (OWTs) are higher than those of wind turbines on land. It is important to select a suitable foundation in the design process of OWTs in order to avoid unnecessary cost loss. The wide-shallow bucket foundation (WSBF), which is known as a new and alternative foundation for OWTs, has currently been elaborately designed and successfully checked (Ding et al., 2015; Zhang et al., 2015). In Qidong, a city in the southeast part of Jiangsu Province in China, a WSBF has been installed at an offshore test facility, as shown in Fig. 1 (Lian et al., 2012; Liu et al., 2015). The WSBF has lots of advantages as a new type of OWT foundation. Firstly, the foundation can be prefabricated on land so that the duration of offshore construction will be shortened greatly. Secondly, its structure reduces the foundation installation cost. The interior of the foundation is divided into 7 tanks, as shown in Fig. 2. It can be towed by the barge from the shore of the prefabrication site to the installation and construction site by inflating tanks. This can reduce the manufacturing and installation cost of OWTs significantly. Thirdly, the WSBF can resist large environmental load. The diameter of WSBF is relevantly large, and the contact area between the top cover and the soil is also large. The skirt and the bulkheads have a good restraint effect on the soil, and can resist the influence of the horizontal and the moment loading on the OWT effectively. Additionally, an arc transition structure (shown in yellow in Fig. 1) has been designed on the top of the bucket foundation in order to make sure that the upper tower can transmit its large loading to the WSBF, and then to the subsoil (Lian et al., 2012).
