Numerical simulation and verification of goaf morphology evolution and surface subsidence in a mine

Abstract

In order to accurately predict the evolution law of the morphological distribution of the goaf and the changes in surface subsidence after mining of the shallow ore body, the No. 6 copper ore body was used as the research object. According to the actual situation of the site, the numerical simulation software COMSOL Multiphysics is used to analyze the shape evolution of the goaf, establish the prediction model for the shape evolution of the goaf and surface subsidence, and make predictions on the scene. The rationality of the prediction model is verified by comparing it with the actual measured surface subsidence results. The results indicate that: (1) As mining progresses, stress concentrations gradually form on both sides of the different sections of goaf, the top plate breaks up and loses its bearing capacity, and stress are transferred to the bottom plate of the deposit and form a stress reduction zone. (2) As mining progresses, the subsidence of the surrounding rock at the top of the goaf increases with the increasing mining area and is transmitted to the upper part of the goaf, eventually leading to surface subsidence and the formation of a concentric sink basin, with the maximum displacement occurring at the centre of the circle corresponding to goaf. (3) By determining the safety of the overlying buildings in goaf, it is concluded that the extraction of the shallow ore body will have little impact on the damage to the surface buildings.