基于耦合理论的海底地震仪设计方法研究

Research of design method for ocean bottom seismometer based on the coupling theory

进行航行舰船地震波观测时,必须考虑海底地震仪(OBS)与海底的耦合问题。由于大部分海底被一层厚厚的松软沉积物覆盖,所以海底地震仪响应会严重影响海底表面的运动。并且海底地震仪位于流体与固体的边界上,浮力的作用也会影响质点运动。对于不同类型的地震波,作用力与质点运动并不满足我们所期望的关系。本文介绍了海底地震仪与沉积物的耦合模型,将其简化为质量-弹簧-阻尼器系统。响应特性主要取决于OBS的质量、结构、刚性以及沉积物密度。通过理论计算,得到影响海底耦合的主要因素,并在此基础上提出海底数字地震仪的合理设计方法。

Coupling of ocean bottom seismometers（OBS） to sea floor must be considered when use seismometer to observe seismic wave for the moving ship.On the ocean floor,the most common medium is thick,soft,low-velocity sediment,so the response of OBS can be strongly affected by the motion of submarine surface.In addition,the seismometer is emplaced at a boundary between a liquid and a solid,and the effects of buoyancy can also strongly affect the particle motion.The motion will not follow the expected relationships between pressure and particle motion for different wave types.In this paper,a model representing the coupling of OBS to the seafloor as a mass-spring-dashpot system has been introduced.Response is strongly dependent upon the mass and configuration of the OBS and the rigidity and density of the bottom material.The main elements affected coupling problem were gained through theoretical calculation.Besides the rational design method of ocean bottom seismometers was suggested from the result.