Seismo-acoustic waves generated by an object impacting on the seabed Conference Paper uri icon

abstract

  • Damage to the ocean environment is often caused by dropping the objects of the size of oil drums packed with toxic materials along the coastal waters. The objective of this study is to be able to detect the event on impact on the seabed. The source detection and identification requires source modeling and is the focus of this study. An object penetrating into the seabed induces a transient force with concomitant waves propagating from the point of impact. Prediction of seismo-acoustic signals emanating from an impacting object requires realistic predictions of force (or deceleration) time histories of the impacting object as well as prediction the waves generated by this impact force. This paper presents the results of investigations for developing an analytical framework for simulating this process, with particular emphasis on objects impacting the seabed. Acceleration time histories for various object types are predicted using an impact penetration model that accounts for the effects of buoyancy, soil shearing resistance, and hydrodynamic drag. Soil shearing resistance, generally the dominant form signals at the geophones as a function of range and depth. The paper presents parametric studies of object impact penetration for various conditions of object geometry and weight, impact velocity, and soil strength and its effects on the received signals. The analyses are applicable to fine-grained seabed sediments for which undrained conditions are assumed to prevail during impact penetration. The deceleration function is used as an input to seismo-acoustic model to predict the received signal. The analytical framework for calculating the deceleration time histories and propagation calculations will then be used for designing the experiments. Signal processing approaches are suggested to detect the object on impact on the seabed.

published proceedings

  • 16th International Congress on Sound and Vibration 2009, ICSV 2009

author list (cited authors)

  • Aubeny, C., Rao, K., & Schmidt, H.

complete list of authors

  • Aubeny, C||Rao, K||Schmidt, H

publication date

  • December 2009