Roof filling control technology and application to mine roadway damage in small pit goaf

To recover coal resources that have been damaged by traditional mining methods and ensure stability of the lower roadway in a small pit goaf, the goaf area must be filled and reinforced. In this research, the 1202 working face of the Hanzui mine is considered as an example for classifying the roof of the mining tunnel under the small kiln destruction zone, the effect of the goaf on the roadway is determined based on the radio tunnel penetration method, a mechanical model to determine the roof filling control mechanism was established, and the duct foaming system and roof filling process were designed. The results show that the scope and degree of influence of the goaf on the mining lane are large, but safe tunneling can be ensured through the use of a steel shed and advanced grouting techniques. When the roof conditions are not similar, materials with different filling heights and filling strengths can be used to control the roof filling of the roadway. By combining field experience and laboratory tests, it was determined that a high-foaming material with a water-cement ratio of 1:0.6, a suitable high-foaming additive, and a water volume ratio of 1:30 is cost-efficient for filling and meets the filling strength requirements. Finally, the reliability of the proposed technology was verified by field experiments, which provide a reference for filling operations in similar mines.