274 / 2023-10-07 12:42:14

The Development History of IFM-KS Model for Studying the Movement Law of Overlying Strata

influence function method,strata movement,key stratum,mining subsidence

According to the Focus Theory, the influence functions method (IFM) was optimized and initially proposed as a two-dimensional surface final subsidence model, which was later refined into a three-dimensional surface final subsidence prediction model for more accurate prediction of surface subsidence. In the year 2000, the application of the influence function method to underground rock movement was expanded by establishing a relationship expression between subsidence parameters (R, d, and a) and strata thickness (h). A continuous two-dimensional prediction model was developed, assuming that underground rock layers are complete and continuous. During the period from 2010 to 2012, the rock layers were uniformly divided, taking into account their hardness characteristics. The relationships between a, R, d, and hardness were determined, further enhancing the predictive model. From 2013 to 2015, a shift away from artificially dividing the rock layers was made, and instead, the natural hardness of the strata was considered. Due consideration was also given to the influence of the key stratum (KS), and the load q on the overlying rock layers was calculated. Parameter R was optimized using mechanical methods. The values of subsidence parameters a and d were obtained through nonlinear regression using data collected from 101 instances of surface and underground subsidence, resulting in improved accuracy. When compared to physical similarity models, a maximum error in subsidence values of only 3.93% was exhibited by the influence functions method and key stratum(IFM-KS) model, and it has been widely applied. Building upon the foundation of the final-state two-dimensional subsidence prediction model, dynamic two-dimensional subsidence prediction models and final-state three-dimensional subsidence prediction models were subsequently introduced, all of which have been widely adopted. Additionally, predictive models for total strain, porosity, permeability, and other parameters were established to characterize the rock stratum damage and overlying strata subsidence conditions. Future research directions include the development of models for multi-layer coal mining-induced rock movement and the continued refinement and optimization of dynamic three-dimensional subsidence prediction models. However, there are still some challenges that need to be addressed.