CARASEDIM (CARactérisation Acoustique des SEDIments Marins) is a project conducted by MAREE and sponsored  by the DGA and began in 2010. It concerns geoacoustical relations in marine sediments involving acoustic parameters (as sound speed) and other physical parameters (as mean grain size). These relations are required for both civil and military applications.

Geoacoustic parameters of the seafloor are required for accurate sonar prediction and analysis of seismic reflection profiles, especially in shallow water. They are generally established by means of empirical relations. CARASEDIM is an experimental project devoted to refine these geoacoustical relations in marine sediments, including coarse sands. The objectives are:

  • establishing geoacoustical relations in coarse sands
  • explaining these experimental results by means of recent physical models
  • conducting experimentations to investigate differences between in-situ and laboratory results
  • conducting experimentations to investigate differences between geophysical inversion results and in-situ ultrasonic results

In 2011, a celerimeter prototype was developed for that purpose. This portative device is equipped with two emitting probes and two receiving probes allowing to transmit  signals between 40kHz and 400kHz. It has been designed for both laboratory and in-situ measurements and first results are promising.

célérimètre développé

The velocimeter prototype