Study On Dynamics Controlling Basis Of System "R-S-F" In Steeply Dipping Seam Mining

When coal seam pitch is more than 35 and longwall caving method along the strike is used, the irregular stowing and binding action of waste from breakage roof along face pitch direction of longwall leads not only abutment pressure distribution and surrounding rock deformation and falling have evident unsymmetrical and time sequence, but also floor fracture and sliding, supports and equipments sliding down or rolling-over at the same time, and system "R-S-F" (roof fracture block-support-floor sliding block) which consists of characteristics above appears dynamic destabilization easily, brings about surrounding rock catastrophes, and causes incidents of safety in production. When coal seam pitch is more than 55 , the characteristics of system "R-S-F" above are more conspicuous and traditional regular longwall along strike (slant arrangement) is not applicable. So the coal seam which pitch is between 35 -55 can be defined as steeply dipping seam.The study on mining methods and equipments of longwall along strike makes less progress in main overseas countries of coal production owing to the complexity of strata behaviors and the features of surrounding rock fracture and movements, and we can seldom see the specialized documents or papers in that field recently. Our country's level in research and test as well as application is world advanced at present.The key of longwall mining along strike safely and efficiently is efficacious controlling of surrounding rock, and the difficult points of surrounding rock controlling are dynamic stability of system "R-S-F" has be made clear by the facts from site test, experimental study and theoretical analysis, and three patterns may cause system "R-S-F" destabilization, such as dislocation, consequentiality and retrogradation among R, S and F in the process of longwall face advancing is put forward in the paper . Then , A analysis dynamic model of system "R-S-F" is set up based on that and general dynamics formulas of system "R-S-F" areobtained through the R-W&Kane's principle and Lagrange's theory. After a feasibility study, the general dynamics formulae are simplified, initial and boundary conditions are given according to the basic requirements of roof and equipments controlling and particular solutions of the formulae are gotten.Because of deformation and load features of system "R-S-F" in longwall face mining of steeply dipping seam should satisfy dynamic coupling equation, the dynamic stability concept which keeps their velocity equal and acceleration zero in the mining process has advanced, and gets the analyzing and calculating methods of working resistance of S (face supports) which is the leading factor of system "R-S-F" when the system is under different destabilization and contact conditions is received in the paper.The foundation of dynamic stability controlling of system "R-S-F" of longwall face in steeply dipping seam mining is F, the key is S, and the goal is R. Among R, S and F, not only S is the factor which may be controlled but also has binding action to R and F, so the systemic stability controlling of system "R-S-F" could be carried out and the goal that cuts down or protects surrounding rock catastrophe and ensures safety in production may be achieved.Finally ,the results from the theory of system "R-S-F" dynamic stability analysis couple closely with ones of traditional analysis ways, and tally with actual situation in production has be made by the test example of face 6134 and 5634 of Lushuidong colliery, Huaying Mining Administration, Sichuan province, and the experimental results which obtained in Shaanxi Key Laboratory of Strata Control makes known and good technology and economic returns have be won.