Research On The Supporting Technology Of Filled Pillar In The Large Section Parallel Abandoned Roadway Of Super Long Working Face

In the fully mechanized coal face,there are some abandoned roadways because of exploration,reconstruction projects of roadways.No matter what form of the abandoned roadway is,when the working face passes through the abandoned roadway,it is impossible to avoid the influence of mining,resulting in the sharp deformation of the surrounding rock of the abandoned roadway.If the effective support can not be provided in time,it is very easy to cause the roof falling,and then lead to more serious accidents.In recent years,because there are few complex practical engineering requirements that the super-long working face needs to pass through the large section parallel abandoned roadway directly in the coal mine,and there are few new attempts to control the abandoned roadway.However,the filled pillar supporting technology introduced from the United States has the characteristics of fast construction speed,direct cutting of shearer,high supporting strength,environmental protection,etc.,which can pass through the large section parallel abandoned roadway quickly and safely The abandoned roadway has outstanding advantages.This paper takes 5314 super-long working face of Chengzhuang Mine as the practical engineering background,which adopts the filled pillar technology to pass through the large cross-section parallel abandoned roadway.FLAC^3D numerical simulation,physical model analysis and indoor tests were used for research,and the optimization and improvement were carried out continuously in practice,and then the following conclusions were drawn:（1）The advantages of simple construction of filled pillar technology and direct cutting of shearer were suitable for the special geological conditions of fully mechanized working face passing through the large section parallel abandoned roadway quickly.（2）Based on the numerical simulation analysis,the physical model of the main roof breaking ahead of workface was established.According to the actual geological conditions,the critical coal pillar width was about 6.34 m,and the support strength required was 4380 k N/m².（3）According to the performance requirements of the filled pillar,the material water-cement ratio in the actual project was analyzed through the laboratory tests.Through the uniaxial compression test of the filled pillar with different height-diameter ratio,it was found that the strength of the samples decreased with the increase of H/D（height-diameter ratio）.When the ratio was greater than 4:1,the strength was steady.According to the uniaxial compression and acoustic emission test of the samples different bearing and yieldable ratios,the ratio selected in the actual project should be greater than 9:1.In order to improve the residual strength of the filled pillar,the bag with constant resistance can make the bearing capacity of the sample decrease step by step after reaching the peak value,and the maximum residual strength can reach 86.69%of the peak value.（4）According to the actual engineering conditions,the layout of filled pillar was designed,and the joint treatment method of coal pillar grouting was adopted.Finally,the maximum roof subsidence in the middle of the tunnel was 130 mm,and the maximum displacement of the two sides was 610 mm.There was no large area of spalls in the coal wall,the 5314workface passed through the abandoned roadway smoothly.