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

Dynamic Response and Stability Analysis of a Submerged Tension Leg Platform
for Paving and Leveling Construction
Meihong Lin*, Linwang Su, Zongquan Ying, Xuegang Wang
CCCC Fourth Harbor Engineering Institute Co., Ltd.
Guangzhou, PR China

immersed tunnel construction because it affects the deformation stability
during construction and operation. An increasing number of tunnels havebeen constructed using the pre-bedding method (Hu, Xie et al. 2015).
This method was used in combination with a specially designed ship toinstall the foundations of the Busan-Geoje Link (Janssen, de Haas et al.
2006) and Hong Kong-Zhuhai-Macao Link (Hussain, Wong et al. 2011).
Leveling ships are designed to reduce the impact of the wind, waves, andcurrent on the leveling accuracy of the foundation and are used for threereasons: installing the pile legs, lifting the leveling structure above thewater surface during construction, and reducing the impact of waves (Hu,Xie et al. 2015). The feeding structure and leveling structure areseparated, and leveling is achieved by the underwater leveling equipment
to reduce the influence of waves and improve the leveling accuracy.
Leveling platforms with a semi-submersible hull are required to reducethe influence of waves.
Tension leg platforms (TLPs) have been widely used for constructing
marine structures (Taylor and Jefferys 1986, Yang and Kim 2011,
Bachynski and Moan 2012). TLPs have the advantage of passive
vibration control (Kandasamy, Cui et al. 2016). A submerged tension leg
platform (STLP) was proposed for an offshore wind turbine in moderatewater depth (70–150 m). The hydrodynamic performance of the STLP
was improved when the platform was submerged slightly during theoperation phase (Han, Le et al. 2017). TLPs have been used in offshore
oil and gas facilities. They are semi-rigid platforms that generatebuoyancy far greater than their self-weight to balance the pretensions int
the legs and provide a relatively stable and safe working environment.
They exhibit good motion performance due to the horizontal pontoons,excellent dynamic performance, and a good safety record.
The potential flow theory has been used for the probabilistic analysis of
the air gap of TLPs and to determine the nonlinear wave elevation andthe platform set-down (Lim and Kim 2019). The smoothed particle
hydrodynamics (SPH) method has been proposed to analyze the effect ofrogue waves (wave incidence angle and mooring line tension) on a TLP(Rudman and Cleary 2013). An analysis of the coupled motion of a TLP
with a semi-submersible system indicated complex coupled behaviors
with multiple natural frequency components (Choi, Nam et al. 2018).
This paper proposes a semi-submersible TLP design, the levelingplatform is semi-submerged, and the pontoons are total-submerged whileworking. The design of mooring system needs to meet the requirementsof working condition and extreme condition, and reduce the total weightby sharing the mooring equipment. The mooring system of working
condition includes the vertical tension legs and the mooring lines

ABSTRACT
A tension leg mooring system based on the three-dimensional potential
flow and dynamic mooring theories is proposed to improve thehydrodynamic performance of a submerged platform. Frequencydomain and time-domain analyses are conducted using ANSYS AQWA
while considering the shallow water effect, the draft of the submerged
platform, and the mooring line and construction-related parameters. The
response amplitude operators (RAOs) of the submerged platform areobtained. As the platform is submerged into the water, the heave and roll
responses and their natural motion periods decrease, improving the wave
stability and adaptability of the platform. The dynamic responses of thesubmerged platform during the working condition are analyzed, focusing
on the motion of the platform at different locations. Time-domain
simulations of the tension leg mooring system are conducted,considering the coupling effect of the heave and roll. The maximum
heave values are obtained for different wind, wave, and current
conditions to reduce the heave and roll motion of the platform. When theleveling machine is located at the corner of the platform, the limit
conditions of the environmental parameters must be considered to meetthe leveling accuracy requirements. Parameter optimization is conducted
for the draft of the platform and the pretension force of the tension leg
under different conditions to improve the leveling accuracy. The
optimized mooring has a leveling accuracy of ± 40 mm. This study
provides an approach to determine the parameters of the tension leg
mooring system for the design of shallow water construction platforms
for water transportation engineering.

KEYWORDS: Submerged tension leg platform; Mooring system;
Hydrodynamic performance; Immersed tunnel; Paving and levelingconstruction

INTRODUCTION
Immersed tunnel engineering is used in road construction to cross rivers
and straits. It has been used since the beginning of the last century and is
widely applied (Lunniss and Baber 2013). Due to the advantages of ashallow buried depth, low foundation requirements, and a short
construction period, immersed tunnel design has been used by many
developed countries globally. This technology has high design andconstruction requirements. The foundation is a crucial aspect of742