Calculation model of overburden subsidence in mined-out area based on Brillouin optical time-domain reflectometer technology

Abstract

With the increase of the coal consumption, the gob scale has become significantly large, increasing the risk of subsidence. Using Brillouin optical time-domain reflectometer (BOTDR) technology, this paper studied the deformation and failure state of overburden above the gob. An overburden subsidence calculation model considering rock mechanical parameters based on the BOTDR was established. In addition, the influence of damage distribution parameters and rock particle contact parameters on the subsidence calculation model was discussed, and the spatial and temporal distribution rule of overburden subsidence was obtained. Taking Zhang Huaizhu working face in Zhangzhuang Coal Mine as an example, this paper verified the accuracy of the subsidence calculation model. The research results show that: The damage distribution parameters have little effect on the overburden subsidence calculation model. The subsidence maximum change caused by the tangential inclination of the particle contact surface in the bulking zone is 0.016 times the height of the bulking zone, while the subsidence maximum change caused by the friction coefficient is 0.046 times the height of the bulking zone. The overburden subsidence of Zhangzhuang Coal Mine has gradually been stabilized after deforming for one and a half year. The ground subsidence in the gob has a negative exponential relationship with time during research period. Compared the result of the subsidence calculation model proposed in this paper with the field monitoring value, it was found that the ground subsidence tendencies are basically the same, and the relative error is less than 8%. It indicates that the subsidence calculation model is reliable in calculating the overburden subsidence in the gob.