Study On Time Function Of Surface-Subsidence Dynamic Under Finite Mining Conditions

Ground surface movement induced by mining is the continuous process which changes with time and space.Generally speaking,Deformation regularity of surface migrating under the Steady Condition is only a special case of the terminate surface movement.In order to assign reasonable work face,and determine appropriate advancing speed of mining face,and control building deformation in time,it is needed to predict the laws,the deformation value and the corresponding positions of any-time surface movement in Mining Process.Therefore,analysis of various buildings is based on dynamic analysis and static analysis.The static prediction of surface subsidence in mining has already been matured in the world at present.Therefore,the main Contents of this paper are dynamic analysis of surface subsidence,establishing the dynamic oretical model and compilation of the corresponding calculation program.Based on the study of time functions during dynamic analysis in mining subsidence both at home and abroad,the probability integral method was used to study the regularity that surface subsidence caused by underground mining varied with the change of time and space,and the coordinate-time functions of dynamic surface movement and deformation was proposed.The coordinate-time functions not only added a variable coordinate-x,but also added several strata movement parameters:q?r?v?????t0,which were unified with the static analysis of probability integral method.Relationship between starting time t0 and the changing coordinate x was studied.Compared to some typical time functions such as Knothe time function,subsidence coordinate-time function w(x,t)could overcome imperfections of first derivative and second derivative that exist in Knothe time function.What's more,the changing regularity of subsidence,subsidence rate,subsidence acceleration,is correctly revealed.Besides,coordinate-time functions of tilt,curvature,horizontal movement,horizontal deformation,etc.could be obtained from partial derivative calculation of x.Then,basic formulae of dynamic analysis in surface movement and deformation were established in conditions of semi-infinite mining and finite mining.The dynamic analysis Predictor is programed with vb,with example analysis.Based on the topic and analysis above,practical verification combined with examples was accomplished.The results showed that the ordinary static analysis function was just a special case of the coordinate-time functions,and the coordinate-time functions correctly described the dynamic process of surface subsidence.Including several well-known strata movement parameters,the coordinate-time functions could fully reflect geological mining conditions and it deserved to be spread widely.The result is illustrated that this method can reflect more accurately the dynamic characteristics of ground surface movement and explain most mining damage phenomena.Dynamic surface ground displacement and deformation is predicted more accurately and more rapid by the dynamic analysis Predictor.It is very useful to direct the mining design and select the building precaution in practice.