106 / 2023-06-15 17:22:21

Mechanism of coal and gas outburst induced by coal softening in normal fault tectonic belt in deep mining

Coal and gas outburst mechanism; Normal fault tectonic zone; Tectonic coal; Outburst control

The coal and gas outburst in deep mining is becoming more and more serious. Most of the coal and gas outburst sites in Pingdingshan mining area occur near normal faults, which have experienced long geological tectonic processes, along which tectonic coal belts with different damage degrees have developed. Born near the normal fault, the normal fault has undergone a long geological tectonic process, and along the fault section there are tectonic coal belts with different damage degrees. In this paper, the evolution law of stress field and deformation field of coal body disturbed under different thickness of coal face in normal fault tectonic belt is studied, and the model of coal softening coal and gas outburst support body in normal fault tectonic belt is put forward, and the mechanism of coal and gas outburst induced by coal body disturbance is revealed. The results show that the thicker the normal fault tectonic zone is, the larger the deformation of the driving face is and the lower the supporting capacity of the supporting body is. Under the vertical mining stress concentration and high horizontal stress, the friction force of the cross section decreases continuously, and the sliding force of the cross section borne by the support body increases continuously. As a result, the tectonic layer in the support body is disturbed and the damage deformation occurs at the earliest, resulting in the damage space of the row coal. The further damage deformation loses the connection with the surrounding energy storage body, and the whole support body will be unstable and outburst will occur. Based on the outburst mechanism, the methods of over normal fault stress relief, energy dissipation and strength improvement of tectonic coal are put forward and field experiments are carried out with good results. The research results can provide important theoretical support for the prevention and control of normal fault coal and gas outburst in the mining process of deep driving face.