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Study on Sound-Speed Dispersion in A Sandy Sediment at Frequency Ranges of 0.5-3 kHz and 90-170 kHz
作者姓名:YU Sheng-qi  LIU Bao-hu  YU Kai-ben  KAN Guang-ming  YANG Zhi-guo
作者单位:National Deep Sea Center, State Oceanic Administration, Qingdao 266237, China,National Deep Sea Center, State Oceanic Administration, Qingdao 266237, China;Laboratory for Marine Geology, Qingdao National Laboratory for Marine Science and Technology, Qingdao 266237, China,National Deep Sea Center, State Oceanic Administration, Qingdao 266237, China,Key Laboratory of Marine Sedimentology and Environmental Geology, First Institute of Oceanography, Qingdao 266061, China;Laboratory for Marine Geology, Qingdao National Laboratory for Marine Science and Technology, Qingdao 266237, China,National Deep Sea Center, State Oceanic Administration, Qingdao 266237, China
基金项目:This work was financially supported by the National Natural Science Foundation of China (Grant Nos. 41330965 and 41527809).
摘    要:In order to study the properties of sound-speed dispersion in a sandy sediment, the sound speed was measured both at high frequency (90-170 kHz) and low frequency (0.5-3 kHz) in laboratory environments. At high frequency, a sampling measurement was conducted with boiled and uncooked sand samples collected from the bottom of a large water tank. The sound speed was directly obtained through transmission measurement using single source and single hydrophone. At low frequency, an in situ measurement was conducted in the water tank, where the sandy sediment had been homogeneously paved at the bottom for a long time. The sound speed was indirectly inverted according to the traveling time of signals received by three buried hydrophones in the sandy sediment and the geometry in experiment. The results show that the mean sound speed is approximate 1710-1713 m/s with a weak positive gradient in the sand sample after being boiled (as a method to eliminate bubbles as much as possible) at high frequency, which agrees well with the predictions of Biot theory, the effective density fluid model (EDFM) and Buckingham''s theory. However, the sound speed in the uncooked sandy sediment obviously decreases (about 80%) both at high frequency and low frequency due to plenty of bubbles in existence. And the sound-speed dispersion performs a weak negative gradient at high frequency. Finally, a water-unsaturated Biot model is presented for trying to explain the decrease of sound speed in the sandy sediment with plenty of bubbles.

关 键 词:acoustic  properties  of  sediment  sound-speed  dispersion  sandy  sediment  bubbles
收稿时间:2015/6/27 0:00:00
修稿时间:2015/11/9 0:00:00

Study on Sound-Speed Dispersion in A Sandy Sediment at Frequency Ranges of 0.5-3 kHz and 90-170 kHz
YU Sheng-qi,LIU Bao-hu,YU Kai-ben,KAN Guang-ming,YANG Zhi-guo.Study on Sound-Speed Dispersion in A Sandy Sediment at Frequency Ranges of 0.5-3 kHz and 90-170 kHz[J].Ocean Engineering,2017,31(1):103-113.
Authors:YU Sheng-qi  LIU Bao-hu  YU Kai-ben  KAN Guang-ming and YANG Zhi-guo
Institution:National Deep Sea Center, State Oceanic Administration, Qingdao 266237, China,National Deep Sea Center, State Oceanic Administration, Qingdao 266237, China;Laboratory for Marine Geology, Qingdao National Laboratory for Marine Science and Technology, Qingdao 266237, China,National Deep Sea Center, State Oceanic Administration, Qingdao 266237, China,Key Laboratory of Marine Sedimentology and Environmental Geology, First Institute of Oceanography, Qingdao 266061, China;Laboratory for Marine Geology, Qingdao National Laboratory for Marine Science and Technology, Qingdao 266237, China and National Deep Sea Center, State Oceanic Administration, Qingdao 266237, China
Abstract:In order to study the properties of sound-speed dispersion in a sandy sediment, the sound speed was measured both at high frequency (90-170 kHz) and low frequency (0.5-3 kHz) in laboratory environments. At high frequency, a sampling measurement was conducted with boiled and uncooked sand samples collected from the bottom of a large water tank. The sound speed was directly obtained through transmission measurement using single source and single hydrophone. At low frequency, an in situ measurement was conducted in the water tank, where the sandy sediment had been homogeneously paved at the bottom for a long time. The sound speed was indirectly inverted according to the traveling time of signals received by three buried hydrophones in the sandy sediment and the geometry in experiment. The results show that the mean sound speed is approximate 1710-1713 m/s with a weak positive gradient in the sand sample after being boiled (as a method to eliminate bubbles as much as possible) at high frequency, which agrees well with the predictions of Biot theory, the effective density fluid model (EDFM) and Buckingham''s theory. However, the sound speed in the uncooked sandy sediment obviously decreases (about 80%) both at high frequency and low frequency due to plenty of bubbles in existence. And the sound-speed dispersion performs a weak negative gradient at high frequency. Finally, a water-unsaturated Biot model is presented for trying to explain the decrease of sound speed in the sandy sediment with plenty of bubbles.
Keywords:acoustic properties of sediment  sound-speed dispersion  sandy sediment  bubbles
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