Layout Of Open-off Cut And Surrounding Rock Control Technology Under Ultra-close Multi-seam In Xinrui Coal Mine

For ultra-close seam, The completeness of lower coal mining front roof of the affected upper coal mining damage, on which in turn is the upper coal seam collapse of waste rock, and after upper coal mining legacy coal pillar in stress concentration plate is formed, leading to the roof structure of the lower seam mining area and stress the environment changes, so that the lower coal mining and coal mining compared to single the emergence of many new rock pressure phenomena.In this paper, by theoretical analysis, numerical simulation, industrial experiment a combination of methods analyze the Xin Rui Coal Mine No.4 coal mining after 5seam in which stress environment, in-depth, systematic study of Close range Seams cut in and deformation of rock stress environment, determine rational layout location and surrounding rock control technology, we have made the following conclusions:(1) The influence of coal mining on the upper pole close the lower seam,obtained after completion mining, coal pillars left edge appears 4 seam face the phenomenon of vertical stress concentration, stress peaks reach 13 MPa, the stress concentration factor of 2.6 so, less stress below the mined-out area, and has been the top 4 coal seam mining floor damage after a depth of about 6m, 4 coal mining affects5 seam roof integrity, consideration shall disposed the upper lower Coal Seam the impact of coal mining.(2) Plastic zones distribution and deformation of the open-off cut in the next seam was obtained when arranged on different positions, The opening cut in mined-out area was disposed below with the outer upper coal pillar off distance of 4m,this time was a small amount of surrounding rock deformation, easy to support.(3) Plastic zones under distribution and deformation of open- off cut tunneling different ways was obtained which to determine the 1501 Face of open- off cut 4.5m using the first excavation and then expand brush into lane way. Determine goaf under the 1501 working face roof for starting cut broken roof, put forward open- off cut mined-out area at the bottom of the supporting technology, when 4 coal seam and the5 coal seam spacing was very small, hydraulic expansion instead of rebar anchor bolt support.(4) Supporting parameters of 1501 working face which was at the bottom of the mined-out area was determined: open- off cut bolt pre-tightening torque was not less than 300 n?m, determine the rebar anchor diameter was 22 mm, failing to rebaranchor construction, selection of 28 mm diameter hydraulic expansion bolt, anchor length was 2.4 m, the top row spacing between bolt was 700 ×700 mm, help row spacing between bolt was 700 mm×800 mm.(5) Open- off cut of 5 coal seam in a coal mine excavation supporting and secondary reinforcement parameters was determined, and a field experiment was carried out, the deformation of surrounding rock control cut, meet the production requirements.