Deformation Mechanism And Stability For Poor Geological Condition Roadway In Tiaoshuihe Phosphorite Mine

With the mining depth increasing,mining technology conditions are more complex,and the stability of underground tunnel is seriously affected.Especially in the poor geological structure and the high stress environment,formation of tunnel excavation and support,to a large extent,affects the benefit of the mining,and hiddens dangers for safety of mining production.Taking the tunnel in the eastern part of Tiaoshuihe Phosphorite mine as the research object,the paper analyzed the stability of the poor geological area 870 which crossed the fault zone,the mining tunnel which was near the fault zone,and the tunnel with weak intercalated roof,and put forward corresponding control countermeasures according to the factors of instability of tunnel.This paper mainly completed the following work:(1)The engineering geological characteristics and field geological investigation of the eastern part of Tiaoshuihe Phosphorite mine was systematically analyzed and researched,The instable tunnels included the poor geological area which crossed the fault zone,the mining tunnel which was near the fault zone,and the tunnel with weak intercalated roof.(2)The paper analyzed the unstable damage mechanism of the surrounding rock in tunnel of poor geological condition area through theory computation,and researched the poor geological area which crossed the fault zone,and the mining tunnel which was near the fault zone using FLAC3 D numerical simulation method.The results showed that occurrences of faults was the important factor which affected the stability of the tunnel across the fault zone.With the increase of the width of the fault,the horizontal stress of the roof existed mutations in the excavation of tunnel,and the maximum ground settlement of the tunnel roof varied largely.With the increase of fault dip angle,all the indexes of surrounding rock increased,but the amplitude of variation was little.The study showed that liner support couldn't meet the demand of the stability of the tunnel,while the shotcreting-bolting support could play a good role.The shotcreting-bolting support could control the roof and floor of the tunnel,but need to improve the bearing capacity of the surrounding rock of tunnel through reducing the cross section area.According to the numerical simulation on the the mining tunnel which was near the fault zone,the results suggested it was necessary to set aside enough safety pillar width when mining tunnel was near the fault;at the same time,it was suggested to avoid the dip mining.Besides,for the mining area with many mining stripes,the fault safety pillar was at least 20 m above.(3)According to the numerical simulation on the tunnel with weak intercalated roof,the results suggested liner support had good supporting effect for weak intercalated roof,while didn't for two sides and floor of tunnel,because the displacement of two sides was 31 mm.Joint support could best control two sides and floor of tunnel.For controlling the tunnel with weak intercalated roof,on the one hand it needs to judge the style of the roof clay interlayer,on the other hand it needs to choose reasonable support forms.