Proceedings of the Thirty-second (2022) International Ocean and Polar Engineering Conference
Shanghai, China, June 5–10, 2022
Copyright © 2022 by the International Society of Offshore and Polar Engineers (ISOPE)
ISBN 978-1-880653-81-4; ISSN 1098-6189

www.isope.org

Study on Bearing Capacity of the Wide-Shallow Bucket Foundations in Two-Layered Clay
Runbo Cai, Run Liu, Jijian Lian, Guodong Sun, Xu Yang, Xintong Hao
State Key Laboratory of Hydraulic Engineering Simulation and Safety, Tianjin University
Tianjin, China

resist large environmental load. The diameter of WSBF is relevantly
large, and the contact area between the top cover and the soil is alsolarge. The skirt and the bulkheads have a good restraint effect on thesoil, and can resist the influence of the horizontal and the momentloading 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 cantransmit its large loading to the WSBF, and then to the subsoil (Lian etal., 2012).

ABSTRACT
Appropriate estimating bearing capacity of bucket foundations
embedded in two-layered soil is a significant subject in geotechnicalengineering. The effects of embedment on the ultimate bearing capacityof wide-shallow bucket foundations (WSBFs) in two-layered clay wereanalysed. A parametric study was performed for the relative thicknessof the upper soil, the relative soil strength, and the depth-diameter ratioof the foundation. The finite element (FE) results were presented interms of the modified bearing capacity factor that reflects the influenceof parameters mentioned above. Different types of failure mechanisms
were described as the above-mentioned parameters changed.

KEY WORDS: Foundations/Footings; relative thickness; relativestrength; depth-diameter ratio; numerical modelling.

INTRODUCTION
As an environmentally friendly energy, wind energy has thecharacteristics of sustainable regeneration and inexhaustibility, so thatthe use of wind turbines to generate electricity is becoming increasingly
common. The offshore wind has huge energy value because it is fasterand more stable. However, installation cost and engineering complexityof offshore wind turbines (OWTs) are higher than those of windturbines on land. It is important to select a suitable foundation in thedesign process of OWTs in order to avoid unnecessary cost loss. The
wide-shallow bucket foundation (WSBF), which is known as a new andalternative 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 inChina, a WSBF has been installed at an offshore test facility, as shownin Fig. 1 (Lian et al., 2012; Liu et al., 2015). The WSBF has lots ofadvantages 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 isdivided 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 andconstruction site by inflating tanks. This can reduce the manufacturing
and installation cost of OWTs significantly. Thirdly, the WSBF canFig. 1. A OWT with the WSBF

Fig. 2. Divided tanks of the WSBFThe unusual structure and installation method of the WSBF, as well as
the complex interaction between the foundation and the soil, make it
difficult to determine the bearing capacity of the foundation. The soil is
usually layered in actual engineering conditions. The failure
mechanism of the layered soil is influenced by factors like the soil layer

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