The Impact Analysis Of Fracture Structure On The Narrow Coal Pillar Stability And Its Control Technology

The stability of narrow coal pillar of fully mechanized caving is closely related to themain roof’s fracture structure of gob-side entry. The narrow coal pillar’s effectively control isimportant theoretical significance to safeguard security,improve recovery working face ofmining in working face and enhance economic efficiency.This article analysis the impact of basic roof structure’s breaking on the narrow coal pillarstability systematically. Achievements of this dissertation have been displayed as follows.(1) Theoretical calculation analysis showed that the height and thickness of basic roofoverlying is11.2m and8.3m respectively, and the rational narrow coal pillar width is4.2m to5.25m. Based on comparative analysis of different width of the narrow coal pillar under theconditions of the narrow coal pillar stress, roadway deformation law, then the conclusion hasbeen drawn that reasonably narrow coal pillar width along the goaf in fully mechanizedcaving is5m.(2) In certain circumstances of basic roof structure’s breaking on the narrow coal pillarstability was considered only, narrow coal pillar’s vertical stress is mainly affected by theimpact of the basic roof of the goaf side length of the key blocks and the fracture line’sposition of the basic roof. Under the same key rock block length condition, the narrow coalpillar vertical stress is minimum when the basic roof fracture position locate above the pillar,and the narrow coal pillar vertical stress is maximum when the basic roof. The narrow coalpillar vertical stress is obviously influenced by the key rock blocks’length and the basic roof’sfracture position fracture position locate in the goaf side.(3) The influence on the stress of coal pillar and surrounding rock deformation by theroadway section size was analyzed, and the influence rule of a different roadway cross-sectiondimensions to the narrow coal pillar vertical stress has been drawn.(4) The detection results show that basic roof fracture position is located in narrow coalpillar near the top of the goaf side. The position of vertical stress peak of the coal body islocated the entity coal wall side between7m and9m with the vertical stress’s peak isapproximately3.6MPa.(5) The tunnel rock support program " high preload cable&high prestressed anchor cablereinforcement " was proposed based on all above analysis.