Stability analysis of anhydrite mine-out as an underground gas storage based on DEM and similarity theory: a case study

This paper describes a comprehensive idea for stability evaluation of anhydrite mine-out used as an underground gas storage, including the inversion analysis of contact model parameters of anhydrite rock and numerical analysis based on discrete element method (DEM). Applying the particle swarm optimisation algorithm (PSO), a unified fitness function was defined based on multiple mechanical parameters of the materials, and the contact model parameters of anhydrite rock based on DEM were back analysed with high precision and efficiency. In addition, the similarity theory was introduced to reduce the size of the practical geotechnical structures and improve the computational efficiency of DEM. Taking Anhui Hengtai Anhydrite mine as an engineering case, the stability of the anhydrite mine-out used as an underground gas storage was evaluated and the optimal internal storage pressure was determined, which provides a reference for the reuse of anhydrite mine-out.