Damage Accumulation and Infrared Differentiation Characteristics of Fractured Rock–Coal Combination
摘要
In order to achieve the objectives of safe support and efficient production in deep mines under high geostress conditions, this study integrates infrared thermography and energy driven theory to investigate the instability and damage patterns of fractured rock–coal combination. The results show that the presence of rock fractures significantly reduces the compressive strength of the samples. The coal remains the primary subject of failure, with the damage zone tending to shift outward due to fractures, a trend that diminishes as the dip angle increases. As the dip angle of the sample fractures increases, the following major changes occur: the peak stress shows a decreasing trend in amplitude (16.97%, 7.42%, and 3.85%, respectively), while the peak strain first increases by 26.93% and then decreases by 0.71% and 3.29%, respectively. The maximum differential temperature (∆TMIR) first decreases by 12.905%, then increases by 7.41% and 27.59%, while the sum of the differential temperature (∑∆TMIR) increases by 36.21%, decreases by 0.07%, and then increases by 33.92%, demonstrating a “rapid–slow–rapid” rising trend. The dissipated energy density due to energy-driven failure shows a trend of “increase (+ 323.52%)–decrease (−35.38%)–increase (+ 29.77%)”, indicating that the proportion of shear damage continues to increase. Based on the stress distribution function obtained at the coal–rock interface, it was determined that the uneven stress transfer and interface deformation at the fractures are the main reasons for the uneven axial stress distribution and enhanced shear damage in the coal body. Based on this, the applicability of infrared monitoring technology in the damage behavior pattern of coal–rock combinations containing fractures is evaluated.