Mechanism Of Bending-Fold Like Floor Heave And Relative Control Technology For Stratified Strata In Deep Mine

In order to solve bending-fold like floor heave problem in deep burial mine, this paper present a research on the basis of theological analysis, numerical simulation, and field trials. it gives a deflection equation for solving the deformation and fracture of strata in floor, such as bending stress and ultimate loading force in strata. It also leads to the solution for divisional slippage fracture in floor and relative movement law, and then it proposes two kinds of contril technologies, they are anti-heave bolting beam and U-shaped closed steel support. The main conclusions are listed as below.(1) Elastic thin plate mechanical model was built based on elastic-plastic theory of plates and shells, solution for bending distortion equation was obtained on the basis of small deflection theory of rectangular plate. In addition, the bending stress in stratified strata in floor was analyzed in view of the critical fracture criterion of bending-fold like floor heave, the lower limiting value for ultimate loading force in key strata in floor is expressed as(2) On the basis of slip line field model for strata instibility in floor, this dissertation divides stratified rock mass in floor into active fracture zone, crush transitional zone, and crush passive zone. Among them, the active fracture zone(floor strata in the downward direction of ribs) can integrally move to the direction angled π4 2j- andπ()4 2j- - with horizon. Strata in crush transitional zone also can integrally rotates based on two points in base angle and orthogonally moves along radical direction, whereas crush passive zone is deformed to the gob side and whose displacement direction is vertical.(3) Instability and fracture procedure of U-shaped steel specified by inverse arch beam was studied, the expression for critical buckling load of two-ends hinged inverse arch was theoretically solved on the basis of the built model. Critical buckling loads, and relationship between ultimate bearing loads and arch height for U25, U29, and U36 specified inverse beams were researched with the aid of ANSYS, the result indicates that the maximum buckling load and the mostly stable loading system can be simultaneously attained when central angle for inverse arch is 70°, or in other words, the arch height is 0.8 m.(4) Mechanical expression for support strength of inverse arch equipped with bolting beam and relative designing/calibration criteria were proposed on the basis ofthe synergetic structural model of inverse arch. According to the solution for internal stress bending moment of U-shaped steel closed support, the maximum uniform load qmax was initiated based on strength check method. Plus, the bearing load for closed support also been calculated by superposition principle, finally, a design thought for closed support begins to take shape.(5) Field tries conducted in-848 west conveyor roadway in Panyidong Mine in Huainan city, and in ingate area of-1015 level in Kongzhuang Mine have testified that the proposed closed support and inverse bolting beam arch were capable of controlling the floor heave, the stability has been sustaining for 3 years. It is especially worth noting that total deformation in Kongzhuang Mine is less than 10 mm. hence, this supporting methodology is reliable and effective, it thus provides a technical route for governing bending-fold like floor heave in deep mines with stratified rock mass hosted.