Rigidity effect of the mine geophone mounting on its frequency response

Abstract

Purpose. To determine the rigidity effect of the changes in mine geophones mounting on the frequency response of the recorded seismoacoustic signals. Methodology. Operational calculus and frequency analysis are used. Findings. The dependences of the frequency characteristics of geophones under coupling conditions with the rock are studied. A possibility is shown of qualitative change in the recorded signal when changing the rigidity of installation of the case of a geophone; moreover, increase in rigidity can result in both increase and decrease in the amplitude of frequency components in a fixed frequency range. The calculations are performed for the parameters characteristic of the current use of geophones and the most common rocks. Electrodynamic velocimeter and piezoelectric accelerometer were considered separately. Originality. Frequency response changes in the seismoacoustic signal recorded by the geophone can be caused by the changes in the rigidity at the coupling between the geophone and the rock. The ratio of the installation frequency to the natural frequency of the geophone can serve as an indicator of the possible rigidity effect. Numerical values of this indicator are proposed. Practical value. Critical analysis of the obtained seismoacoustic data, taking into account the possible changes in the geophone installation rigidity in the measurement time. The need to determine the frequency of the geophone mounting in their initial mounting and periodic control to this parameter for further operation.