基于Buckingham模型和Biot-Stoll模型的南沙海域沉积物声速分布特征

Sound Speed Distribution of Seafloor Sediments in Nansha Islands Sea Based on Buckingham Model and Biot-Stoll Model

为了选择合理的南海南部海底沉积物的声速反演模型,分别利用Wood方程、Buckingham模型、Biot-Stoll模型等声波传播理论模型计算了沉积物的纵波声速,结合沉积物实测声速和物理参数等,对比了模型计算声速与实测声速的变化特征。声速实测值与模型计算值的对比表明,Buckingham模型计算值与实测值的平均偏差最小。研究区实测声速比和模型计算声速比的分布表明,声速的变化特征与沉积环境具有相关性,声速模型计算值与实测值具有相似的变化特征;模型计算声速与实测声速的垂向变化规律不相同,模型计算声速随深度基本不变,而实测声速在陆架、陆坡和海槽等沉积环境中呈现出多种垂向分布特征。研究结果认为,侧重于沉积物孔隙性的Biot-Stoll理论仅适用于陆架区粗颗粒沉积物,兼具流体和弹性固体双重性质的Buckingham理论具有更广的适用范围。该研究对获取南海南部海域沉积物声速分布特征有重要意义,可为多波束测深或浅地层精细解释等提供基础资料。

In order to analyze the application of the speed theoretical models to predicting the sound speed of sediments in the southern South China Sea, the authors calculated the sound speed by using Wood equation, Buckingham model, and Biot-Stoll model respectively. The comparison between the calculated and the measured sound speeds shows that the average deviation between the calculated sound speeds with Buckingham model and the measured sound speeds is smaller than the calculated values with Wood equation and Biot-Stoll model. The comparison of the sound speed ratio distributions indicate that the calculated sound speed ratios with Buckingham model and Biot-Stoll model have the similar horizontal distributions with the measured sound speed ratios. The sound speeds have different horizontal distributions in different sedimentary environments and are closely related to the physical properties and the deposition of sediments. The calculated sound speed ratios are invariant with the depth, while the measured values have different vertical distributions in several different geomorphic units. According to the comparison results, the Biot-Stoll model is only suitable for the coarse sediments in the continental shelf, and the Buckingham model is more applicable to predicating the sound speed of sediments in the study area. The research is significant in obtaining the sound speed distribution of the sediments in the southern South China Sea, and can provide reference for the multi-beam echo sounding and the sub-bottom survey.