Analysis Of The Deformation Characteristic And The Stability Of The Roof-pillar System Of Mined-out Areas

With the acceleration of the urbanization process and the increasing density of roadnetwork facilities, available land resources are decreasing, some structures such ashighways, bridges and tunnels have no choice but to across the mined-out areas. Therefore,how to do the risk assessment reasonably to the shallow mined-out areas is the urgent andchallenging problem in the present engineering practice.Based on the research background of the shallow mined-out areas of JingYang coalmine in Antaibao open-cast mine, the problems of the roof bending deflection with mixedboundary conditions under uniform load, disturbance effects analysis of the coalpillar-roof system caused by a sudden instability coal pillar and the separation anddislocation characteristics of the layered roof in the mined-out areas under differentconditions have been analyzed by adopting theoretical analysis method and numericalcalculation method, and some research results have been obtained as followed:Firstly, based on the Reissner’s thick plate theory, this paper derived the function ofroof bending deflection with mixed boundary conditions in the mined-out areas underuniform load by the method of reciprocal theorem and gave the analytical solution;besides, this paper analyzed the different characteristics of roof bending deflection withmixed boundary conditions and simply-supported ones; then this paper has analyzed thenonlinear characteristics of the maximum bending deflection of the roof changing with thefree boundary length of the mixed boundary.Secondly, this paper built the computational model by using FLAC3D, analyzed thedisturbance effects of the pillar-roof system caused by a sudden instability coal pillar, andstudied the relationship between the gradual evolution process and the strain energyentropy changes of the coal pillar-roof system.Finally, combined with actual project, this paper analyzed the separation anddislocation characteristics of the layered roof in the mined-out areas under differentconditions by adopting numerical calculation method.