Identification of burning temperature of burnt rocks in northern Shaanxi based on thermoacoustic emission technology

The identification of the burning temperature of burnt rocks has important guiding significance for the formation and evolution of burnt rocks. Based on the thermal Kaiser effect, the threshold temperature of burnt rock in Zhangjiamao, Shenmu, Northern Shaanxi Province is predicted through the acoustic emission (AE) acumulated energy and the changes of parameters RA (rise time/amplitude) and AF (average frequency) during heat treatment. The results show that the thermoacoustic emission characteristics of burnt rocks can effectively identify the burning temperature of burnt rocks, and it is basically consistent with the petrographic analysis of the temperature experienced by the burnt rocks. There is a significant formation burning temperature gradient in the burnt rocks in the study area. For the rocks in the first to the fifth layers, the burning threshold temperature increases gradually; for the sixth to the seventh layers of rock, the maximum temperature exceeds 700℃; for the eighth layer of rock, the threshold temperature is 245℃. When the heat treatment temperature is low, the intergranular tensile cracks develop in the rock. When the temperature exceeds 600℃, the proportion of transgranular shear cracks begins to increase, and the AE signal increases twice. At the same time, there is a quiet period of AE, and there are multiple platforms in the cumulative energy curve. The identification and zoning of burning temperature of burnt rocks, it has important practical significance for water control of coal mine and stability of surrounding rock.