Diagnostics of the acoustic properties of unconsolidated media under natural conditions

Results of experimental studies carried out at the Bezvodnoe test area in 2005 and 2006 are presented. The goal of the studies is to investigate the potentialities of vibration diagnostics of the surface layers of soil under natural conditions. The most attention is given to the problem of measuring the shear modulus of soil and determining the power of seismic acoustic radiation with the help of an impedance method. The results obtained testify to the high sensitivity of the impedance method soil diagnostics and to the possibility of monitoring the variations of soil properties. Sources of nonlinear distortions and the problem of stability of radiation characteristics are also considered. A comparison with theoretical estimates is performed. It confirmed a special role of the contact region as the major source of radiation signal distortions. The results of the study are important for seismoacoustic investigation of the structure of natural media under natural conditions.     

Application of a mobile seismoacoustic system for studying geological structure and prospecting for inhomogeneities to a depth of 100 m

The results of a practical evaluation of a mobile seismoacoustic system intended for the search for underground engineering structures and their imaging are presented. The system was designed at the Institute of Applied Physics of the Russian Academy of Sciences and consists of an electrodynamic radiator of seismoacoustic waves that operates in the frequency range 200–800 Hz, an array of receivers, and a computer-based control unit. The signal is controlled digitally, which allows the system to store up to 10³ realizations. The signal is received by high-sensitivity seismic sensors, amplified by low-noise amplifiers, supplied to a 16-channel A/D converter, and displayed on the computer monitor. The system was used in a field experiment to determine the location of an antilandslide drainage adit.