Journal of Marine Sciences ›› 2023, Vol. 41 ›› Issue (4): 57-69.DOI: 10.3969/j.issn.1001-909X.2023.04.006

Previous Articles     Next Articles

Simulation study on oblique in situ acoustic longitudinal wave measurement of seafloor inhomogeneous sedimentary layer

WANG Ying1(), TAO Chunhui1,2,*(), ZHANG Guoyin2, ZHOU Jianping2,3, SHEN Honglei4   

  1. 1. School of Oceanography, Shanghai Jiao Tong University, Shanghai 200030, China
    2. Key Laboratory of Submarine Geosciences, Second Institute of Oceanology, MNR, Hangzhou 310012, China
    3. Technology Innovation Center for intelligent Ocean Observation, MNR, Hangzhou 310012, China
    4. State Key Laboratory of Intelligent Construction and Healthy Operation and Maintenance of Deep Underground Engineering, China University of Mining and Technology, Xuzhou 221116, China
  • Received:2023-02-14 Revised:2023-03-25 Online:2023-12-15 Published:2024-01-30

Abstract:

Acoustic characteristics of seafloor sediments are the basic elements of marine sound field calculation and engineering geological evaluation. In situ measurement is an effective means to accurately obtain acoustic characteristic parameters. The structure stratification characteristics and the existence of geological anomalies such as boulders lead to vertical and lateral heterogeneity, and the existing acoustic in situ measurement system is difficult to detect and recognize the nonuniform features, and there is a lack of discrimination reference for the identification of stratigraphic non-uniformity. In this study, an oblique acoustic in situ longitudinal wave measurement method based on the heterogeneity of seafloor deposition was proposed, and a simulation study on the oblique acoustic in situ measurement of sediments within a hundred meters was carried out by using the finite element method. According to the data of regional geological engineering exploration data in the East China Sea, three models of uniform sedimentary layer, stratified sedimentary layer, and a sedimentary layer containing the boulder were constructed, and a simulation of acoustic velocity measurement in the sedimentary layer was carried out based on oblique in situ measurement method. The results show that the oblique in situ measurement method was effective in identifying the inhomogeneity in the large-depth sedimentary layer. By introducing the concept of equivalent offset, the original acoustic velocity calculation formula was improved, effectively improving anomaly identification accuracy. The oblique acoustic in situ measurement method proposed in this study was an effective extension of the existing in situ measurement methods of sedimentary layers, which will help to promote the further application of in situ measurement in marine engineering surveys.

Key words: seafloor sedimentary layers, oblique acoustic in situ measurement, acoustic characteristic, simulation

CLC Number: