Study On The Rheological Model Of Overburden Strata In The Mining Field And Mining Subsidence Prediction

In the current theory of mining subsidence prediction, the basic method is to predict the un-subsidence area by the experience from the area where the subsidence has occurred, which is very blindness. By the way, the prediction is mainly made statically. The development of the rheological theory and computer technology provide a sound base to understand the movement law for mining overburden strata and surface subsidence.The thesis propose the visco-elastic model in different phases theoretically, gives out the law of overburden rock strata movement and surface subsidence depending on time in the view of rheology. By performing the similar material simulating experiment, the thesis makes analysis on serial variations of the value of subsidence, horizontal displacement, subsidence velocity, and the position of maximum subsidence in the course of movement for rock strata, tofurther verify the rheological model and the character of phase-dividing, i.e. accelerate subsidence phase of under-developed mining and deteriorate compacting phase of developed mining. On the other hand, gives detailed description on the influence of mining to the deformation character of overburden strata.The thesis has built up a mechanical model of rock, strata subsidence based on the theory of slip line field which is more reasonable to predict the range of mining influence zone. By using the plastic thin slab theory, the first caving space i.e. the starting distance of surface movement is calculated out which provide the condition of determining the range of mining influencing zone.Besides, the regulation of variation for vertical and horizontal stress distribution in the mining field is provided by the finite element numerical analysis to further verify the nature of stage-advancing in time and area-dividing in space, which laid a solid condition for further research on the other aspect of fissure expanding and rock block sliding along the plane etc. affecting the rheological character of rock strata.In the thesis, the calculating method of model parameters is given, and the parameters are derived by reverse analysis on theactual measurement. The prediction model reflects the surface subsidence law well by using the derived model.Meanwhile, the author put forward the concept of surface retardation time which can be taken as both degradation index of mining influence and separating point to subsidence stages.