Accounting for refraction in sonar surveys of mine workings

Abstract

In the presence of a gradient of sound propagation velocity in the location medium, the trajectory of sound rays deviates from straight lines perpendicular to the surface of the sound wave front. Refractive deflection of the rays occurs in the direction of the region of the medium with a lower sound propagation velocity. Obviously, the curvature of sound rays leads to a shift of the sonicolocation irradiation spot on the reflecting surface of the location object. This displacement determines the error of the sonicolocation measurement, and in some cases can lead to the formation of an acoustic shadow zone in which sonicolocation measurements are practically impossible.

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