Determination and Application of Filling Body Parameters of Flexible Moulded Pier Columns for Gob-side Entry Retaining in Fully Mechanized Caving Face with Large Mining Height
In view of the characteristics of strong dynamic pressure disturbance and difficult stability control of surround-ing rock in gob-side entry retaining of large mining height fully mechanized caving face,taking 16402 fully mechanized caving face of Laoshidan Coal Mine as the engineering background,theoretical analysis,numerical simulation and engineering meas-urement are adopted.Firstly,the instability characteristics of roadway under the condition of large mining height fully mecha-nized caving are analyzed.Based on this,the mechanical model of interaction between roof and filling body of gob-side entry re-taining is established,and the support resistance of flexible moulded pier columns is determined.The stress distribution and de-formation law of surrounding rock of gob-side entry retaining under different width and interval of flexible moulded pier columns are analyzed by FLAC3D numerical simulation software.The results show that with the increase of the width of the flexible moul-ded pier column and the decrease of the interval,the peak value of vertical stress in the pier column decreases continuously,the roof subsidence decreases continuously,and the roof subsidence gradually evolves from asymmetric distribution to symmetrical distribution.Based on the stress,deformation law and economic factors of surrounding rock in gob-side entry retaining,the width of flexible moulded pier column in 16402 fully mechanized caving face is determined to be 2 m and the interval is 1 m.After the implementation of the scheme,it is found that the maximum subsidence of the roof of the gob-side entry retaining is 329 mm,the maximum displacement of the coal side is 217 mm,and the maximum displacement of the pier column is 25 mm.The surrounding rock of the gob-side entry retaining is basically stable,which can provide reference for similar projects.
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