Study on Multiparameter Precursory Information Identification of the Fracture of Yellow Sandstone

Abstract EN

In order to explore the disaster caused by uncontrollable instability of coal and rock mass, a multiparameter fusion system is constructed to predict and predict disasters more accurately by identifying the mechanical and acoustic precursors of coal and rock fracture.

In order to explore the precursor information of yellow sandstone rupture, the damage evolution process of yellow sandstone is analyzed from the four aspects of rock mechanics, acoustic emission time domain, frequency domain, and characteristic parameters, and the body strain, dissipated energy and acoustic emission counting, acoustic emission energy, average frequency, peak frequency, b value, and entropy value precursor information identification points are obtained, and 8 parameters are analyzed by time series fusion.

The specific conclusions are as follows: body strain in the violent stage of damage evolution, the slope is zero, the zero end point is the precursor information identification point, the dissipative energy curve overall shows the “s” type, the early growth rate is faster—the medium-term stability—the later period is slowed down, and the upper slope boundary point of the “s” type curve is used as the precursor information identification point.

In the violent stage of damage evolution, the layered features of the acoustic emission count are obvious, the specific gravity shift is more obvious, and the high count appears as the precursor information identification point; the acoustic emission energy accumulates the high-energy signal and is accompanied by the steady and rapid growth of energy as the precursor information identification point.

The effects of shearing main cracks, shear microcracks, tensile cracks, and composite cracks on the acoustic emission count and energy in the damage evolution process are analyzed.

The increase of medium- and high-frequency signals and the reduction of high-frequency signals predict the rupture.

The average frequency signal change law is continuous high frequency-blank-continuous high frequency, with the blank period end point as the damage precursor identification point; the b value damage evolution stage shows a continuously steady increase to a rapid increase, with the continuous stable growth starting point as the crack identification point.

In the process of damage evolution, the sample entropy presents an orderly, chaotic, disordered, and orderly process.

The end of chaos and the beginning of disorder are used as the prejudging demarcation points.

Based on the time sequence, an eight-parameter comprehensive early warning system is constructed.

The indicators are classified into five levels for early warning in the stage of severe damage evolution.

The identification of multiparameter precursory information of yellow sandstone provides a new research idea and analysis angle and method for the failure of other coal and rock masses.