Underground space reservation and surface subsidence prediction based on key pillar mining and backfilling

As the core technical scheme to protect the surface buildings (structures) in the mining area, the short-wall continuous mining and filling technology plays an irreplaceable role in the field of mining. The jump mining distance and the control characteristics of overlying strata are the key factors affecting the construction scope of underground space and the stability of overlying strata, which directly determine the safety and reliability of mining engineering. Different skip mining modes will form different underground space structures, and the scientific and reasonable comprehensive development and utilization of these underground spaces is an important breakthrough to fully tap the added value of filling mining and improve the comprehensive benefits of resources. In order to effectively control the stability of overlying strata in goaf, based on the short-wall paste continuous mining and filling technology, this study proposes a collaborative optimization method of continuous mining and filling and key pillar filling. On the basis of traditional filling technology, the space utilization rate and economic benefits of goaf are further improved. In this paper, three kinds of skip-mining modes and corresponding bearing structures are designed, which are named as Common Single Stripe Elements Backfilling while Mining (CSEBM), Trinity Stripe Elements Backfilling while Mining (TRSEBM) and Twosome Stripe Elements Backfilling while Mining (TWSEBM), respectively. The corresponding supporting technology and parameters are optimized, and the stress distribution characteristics under different filling skip-mining modes are revealed by COMSOL numerical simulation. Based on the geological conditions of a mining area in Shanxi Province, this paper uses the probability integral method to predict the surface subsidence law after mining, and obtains the surface subsidence, horizontal movement, horizontal deformation and curvature distribution characteristics under different skip filling methods. The comparative analysis shows that the surface settlement, horizontal displacement, deformation and curvature of the scattered pillar filling scheme are the smallest, and the damage area of the filling column itself is small, which can significantly improve the volume efficiency of space construction, and lay a solid foundation for the deep development and diversified space utilization of underground space resources.