Dynamic Prediction Model of Overburden Settlement in Deep Mining Areas based on Space–Time Relationship

Depletion of shallow mineral resources caused by deep mining has become an inevitable trend, and deep mining can increase safety accidents and geological hazards. Overburden in a mined-out area is affected by mining disturbances, resulting in its subsidence or collapse, posing a threat to downhole safety and surface ecology. To identify the limitations of existing models, they were studied and analyzed for predicting the overburden movement in a current goaf. Based on the actual dynamic settlement of the overburden at a mine project site, the type and time relationship of the overburden settlement in the goaf is studied. Considering the influence of the deep overburden by self-gravity and tectonic stresses and combining with the Knothe time function, the overburden settlement is classified into four types: (I) sinking at a constant speed, (II) accelerated sinking until collapse, (III) initial accelerated sinking, followed by deceleration of sinking, and finally reaching a stable state, and (IV) initial accelerated sinking, followed by decelerated sinking, and finally accelerated sinking until collapse. A new method for predicting the dynamics of overburden settlement in mined-out areas is proposed based on the relationship between the settlement time, space, and volume. A dynamic prediction model of the settlement dynamics in the mining overburden in a mined-out area was constructed, which can predict the settlement patterns of various types of mine overburden. Finally, the results predicted by the model were validated by real engineering cases and were found to be in good agreement with the actual test results.