Three-Dimensional Seismic Response Analysis of Zhubi Reef in the South China Sea

Reef islands are valuable terrestrial resources for ocean exploitation and utilization but face the serious threat of earthquake disasters. This study takes Zhubi Reef in the South China Sea as the research object and establishes a three-dimensional (3D) reef-seawater model to investigate the seismic response of Zhubi Reef. The 3D local topography and the effect of fluid-solid interaction are comprehensively considered. The artificial boundaries of fluid and solid domains are adopted to simulate the wave radiation and absorption of the semi-infinite seabed and the infinite seawater layer. The boundary substructure method is used to input the seismic waves into the numerical reef models. The results indicate that the seismic responses, including the peak values of the ground motions and the acceleration response spectra, are significantly amplified over Zhubi Reef. The acceleration response spectra on the reef flat shift closer towards the low-period direction compared with those of the seismic waves input from the subsea bedrock. In addition, the 3D topographic effect on the seismic response of Zhubi Reef is studied through a comparative analysis between two-dimensional (2D) and 3D reef models. The distribution laws of the peak response in the middle region of the reef flat calculated by the 2D and 3D models agree well with each other, and the differences are obvious in the edge areas where the local 3D topographies change drastically.

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Three-Dimensional Sound Propagation in the South China Sea with the Presence of Seamount

Journal of Marine Science and Engineering ◽

10.3390/jmse9101078 ◽

2021 ◽

Vol 9 (10) ◽

pp. 1078

Author(s):

Shenghao Li ◽

Zhenglin Li ◽

Wen Li ◽

Yanxin Yu

Keyword(s):

South China Sea ◽

South China ◽

Sound Propagation ◽

Three Dimensional ◽

Sound Field ◽

The South China Sea ◽

China Sea ◽

3D Effects ◽

Horizontal Refraction ◽

2D And 3D

Seamounts have important effects on sound propagation in deep water. A sound propagation experiment was conducted in the South China Sea in 2016. The three-dimensional (3D) effects of a seamount on sound propagation are observed in different propagation tracks. Ray methods (BELLHOP N×2D and 3D models) are used to analyze and explain the phenomena. The results show that 3D effects have obvious impacts on a sound field within a horizontal refraction zone behind the seamount because some sound beams cannot reach the receiver for the horizontal refraction effects, which impacts the sound field within a certain angle range behind the seamount. The arrival structure results show that the eigenrays after horizontal reflection will arrive at the receiver earlier than those obtained from the two-dimensional (2D) model within the horizontal refraction zone behind the seamount. This means that the horizontal reflection effect of a seamount will cause the shortening of sound propagation paths. Finally, in the reflection zone in front of the seamount, the 2D and 3D TL results show that the shape of the reflection zone is similar to an “arch” type, and the horizontal refraction of sound waves has little effect on the TLs in the reflection zone of a seamount.

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THREE-DIMENSIONAL BASIN-SCALE OCEANIC TRANSPORT OF RIVER-DERIVED MICROPLASTICS IN THE SOUTH CHINA SEA

Journal of Japan Society of Civil Engineers Ser B2 (Coastal Engineering) ◽

10.2208/kaigan.76.2_i_979 ◽

2020 ◽

Vol 76 (2) ◽

pp. I_979-I_984

Author(s):

Kosei MATSUSHITA ◽

Yusuke UCHIYAMA ◽

Naru TAKAURA ◽

Taichi KOSAKO

Keyword(s):

South China Sea ◽

South China ◽

Three Dimensional ◽

The South China Sea ◽

The South ◽

China Sea ◽

Basin Scale ◽

Oceanic Transport

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Three-dimensional numerical model study of the residual current in the South China Sea

Oceanologica Acta ◽

10.1016/s0399-1784(03)00053-7 ◽

2003 ◽

Vol 26 (5-6) ◽

pp. 597-607 ◽

Cited By ~ 11

Author(s):

Shuqun Cai ◽

Qizhou Huang ◽

Xiaomin Long

Keyword(s):

Numerical Model ◽

South China Sea ◽

South China ◽

Three Dimensional ◽

Residual Current ◽

The South China Sea ◽

The South ◽

China Sea ◽

Model Study ◽

Numerical Model Study

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Viscoelastic Boundary Conditions for Multiple Excitation Sources in the Time Domain

Mathematical Problems in Engineering ◽

10.1155/2018/7982342 ◽

2018 ◽

Vol 2018 ◽

pp. 1-11

Author(s):

Chen Xia ◽

Chengzhi Qi ◽

Xiaozhao Li

Keyword(s):

Finite Element ◽

Seismic Response ◽

Time Domain ◽

Seismic Waves ◽

Three Dimensional ◽

Seismic Loads ◽

Element Analysis ◽

Artificial Boundaries ◽

The Time Domain ◽

Transmitting Boundaries

Transmitting boundaries are important for modeling the wave propagation in the finite element analysis of dynamic foundation problems. In this study, viscoelastic boundaries for multiple seismic waves or excitations sources were derived for two-dimensional and three-dimensional conditions in the time domain, which were proved to be solid by finite element models. Then, the method for equivalent forces’ input of seismic waves was also described when the proposed artificial boundaries were applied. Comparisons between numerical calculations and analytical results validate this seismic excitation input method. The seismic response of subway station under different seismic loads input methods indicates that asymmetric input seismic loads would cause different deformations from the symmetric input seismic loads, and whether it would increase or decrease the seismic response depends on the parameters of the specific structure and surrounding soil.

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