A Dissertation In Survey Engineering Study On Surface Subsidence Rule Of Thick Alluvium Coal Mining And Prediction Method

The thickness of unconsolidated layers in Huainan new mining area is generally 140-580m,which belongs to the geological and mining conditions with thick alluvium covered.The mechanism of mining subsidence and the law of time and space are quite different from conventional.Literature researches indicated:it is not yet accurate to grasp the subsidence law of the thick alluvium in Huainan mining area and establish the scientific prediction method of surface movement and deformation presently,which seriously restricts the "under buiding,water body,railway and main laneway" coal pillar setting and coal mining production practice in this area.To the deficiency above,in this paper,according to the measurement analysis,numerical simulation and theoretical research,Huainan mining area is taken as an example to carry out the correlation between dynamic/static laws of mining subsidence and geological and mining conditions and the research on fusion method of multi-source heterogeneous deformation prediction model under the condition of thick alluvium systematically.The main achievements of this paper are as following:(1)Based on measured datum,the paper analyses the correlation among of the probability integral parameters,angular parameters of movement basin and geological and mining conditions.First of all,I collected surface movement observation station datum in thick alluvium in Huainan mining area through the literature search.Then,I establish quantitative empirical models of the probability integral parameters(subsidence coefficient q,horizontal movement factor b,main effecting angle tan?,inflection offset coefficient S/H0 and propagation coefficient of extraction k),parameters of movement basin(downward boundary angle ?0,uphill boundary angle ?0,trend boundary angle ?0,downward displacement angle ?,uphill displacement angle?,trend displacement angle ?,advance angle of influence ?,the angle of maximum subsidence velocity ?)and geological and mining conditions(thickness of losses bed,thickness of strata,mining height and workface size).And I also construct the nonlinear prediction model of subsidence coefficient q and geological and mining condition,and test the reliability of prediction model based on forecast principle of BP neural network.(2)Surface subsidence rules of thick alluvium are revealed by numerical simulation with FLAC3D.Based on the geological and mining conditions of Huainan mining area,the FLAC3D numerical simulation model for Huainan mining area is established.The relationship between the thickness of loose layer,mining height,the height of D3/H0 and the maximum subsidence value,the maximum horizontal movement value and the surface subsidence coefficient under thick loose layer are analyzed further by using the method of controlling single factor variable,which fully reveals the influencing factors and the disturbance mechanisms of the subsidence law under thick loose layer condition.(3)The fusion model of deformation dynamic prediction based on multi-source heterogeneous method is constructed.Based on the analysis of the advantages and disadvantages of mining subsidence prediction model based on deformation cause and time series,the four kinds of time-series deformation prediction methods,such as ARMA model,GM(1.1 model,cubic exponential smoothing model and Kalman filter are selected,which with high precision and good complementarity,the fusion criterion is deduced and the dynamic prediction fusion model of multi-source heterogeneous deformation in mining subsidence is constructed.Finally,the model is applied to a thick loose layer covered mining subsidence prediction,results show that the subsidence and horizontal movement of multi-source fusion model prediction accuracy and reliability are better than single model,the reliability of the model was verified.