Modification of a wideband spectral-acoustic method for controlling stress state of a face space

Abstract

To control and manage a stress state of an underground working face space it is important to measure the components of actual stresses. Traditional method for relieving a core-sample with central drill is time and labour consuming and is characterized by a lack of accuracy. To improve these issues geophysical methods which do not interfere with mining are to be used for controlling stress state. Acoustic methods are less time and labour consuming. Justification of spectral-acoustic method modification for controlling stress state of a face space is introduced. It is done on the basis of the dependence of the acoustic signal of the operating equipment amplitude-frequency response median on average stresses. The acoustic signal is recorded in the entire sensitivity band of the geophone. The description of a flow chart and operating principle of intrinsically safe portable device for implementing the modification in mines on the seams dangerous on gas and dust and prone to sudden coal and gas outbursts and rock bursts are given. The device operates in three modes: determining amplitudes of background noise and setting signal amplification coefficient; controlling stress state while generating continuous acoustic signal produced by operating mining equipment (combined machine, drilling device, plough-type machine) into the massif; control of stress state during generation a discrete acoustic signal produced by artificial source (heavy hammer strokes) into a massif.