Mining Scale Effect Of Roof Strata Movement Law In Fully Mechanized Mining Face

In China's energy structure,coal will still occupy an important position.With the development of science and technology,the comprehensive mechanized mining method has been widely used in the production of coal mines.Field practice shows that different mining parameters have different effects on roof subsidence,maximum abutment pressure and roof failure height of working face,which leads to roof pressure changes and roof support problems.Aiming at the above problems,this paper studies the influence of different mining parameters on the roof strata movement law,so as to improve the control theory of mine pressure and strata,and use it to guide the mining practice,so as to ensure the safety and efficiency of mine production.Taking 1803 fully mechanized mining face of Shaping Coal Mine as the research background,the comprehensive research method of theoretical analysis,numerical simulation calculation and field measurement is adopted to analyze the rule of different mining parameters on the roof strata activity.The main research results are as follows:1.Based on the key layer theory and elastic mechanics,the expressions of the initial pressure stepping distance and the periodic pressure stepping distance of the working face are analyzed and obtained.Combined with the geological data of 1803 working face in Shaping Mine,the initial pressure stepping distance is calculated to be 54.39 m and the periodic fracture stepping distance is 22.52 m.The direct roof strata of No.8 coal seam in Shaping Coal Mine belong to two types of moderately stable roof,and the basic roof strata are ? grade to compress the strong roof.Based on the empirical formula for the selection of hydraulic support selection,Shaping mine 1803 working face USES ZY8000/20.5/40 hydraulic support.2.Establish a numerical calculation model for 1803 fully-mechanized mining face,select the roof subsidence,maximum abatement pressure and roof failure height of different advancing distances(20m,50 m and 80m)of the working face,and analyze the relationship among mining height,buried depth and working face length.The multiple linear regression equations of roof subsidence and working face height,buried depth and working face length are summarized as follows: S= 0.93 m + 0.079 h +0.0058L-7.14;The multiple linear regression equation of the maximum abutment pressure and working face height,buried depth and working face length is as follows:P=0.98m+0.07h+0.0021L-4.75;The multiple linear regression equation of roof failure height and working face mining height,buried depth and working face length is H=0.926m+0.046h+0.0071L-1.315.By using range analysis method,the primary and secondary order of influencing factors are determined as follows:buried depth,mining height and working face length.3.According to the measurement research on the working resistance of 1803 working face support in Shaping Mine,the rule of periodic pressure step is observed.In the three times of periodic pressure observed in 1803 fully mechanized mining face,the measured average step distance of periodic pressure is 25.4m.It is basically consistent with the theoretical calculation period and the pressing step distance is 22.52 m.The mean values of dynamic load coefficients in three periods are 1.26,1.23 and 1.27,respectively.4.By predicting the failure height of overburden through theoretical formula and numerical simulation regression formula,it can be concluded that the failure height of overburden is 8.85 m during the mining process of Shaping Mine,which provides certain experience for the continuous mining of working face and guiding the mining of other working face.According to the measured cycle to pressure step distance and support load and other data,8 methods are used to check the working resistance of the selected ZY8000/20.5/40 type support on the working face.The average working resistance of the 8#coal seam support is predicted to be 7042 k N / Frame.Therefore,it is appropriate to choose ZY8000KN/frame maximum working resistance of 20.5/40 hydraulic support,which can meet the mining needs of the working face,and retain a certain amount of affluence.