Stability Analysis Of Rock Pillar In The Uncovering Coal Process Of Highway Tunnel Though Coal Seam

With the development of transport network, more and more tunnels ware constructed. But because of the complexity of geological conditions, an increasing number of the tunnel has to pass though coal seams, which are often accompanied by gas disasters, including the Coal and gas outburst.At present, the method used to prevent Coal and gas outburst in high way tunnel construct when pass though coal seams is described as follow: firstly reserving a certain thickness safety rock pillar before uncovering coal seam, and then the action of preventing the coal and gas outburst to dangerous coal seam is took, finally uncovering the coal seam. So the study on stability of the rock pillar has important theoretical and practical engineering significance.In this paper, the stability of the rock pillar between the coal seam and excavation face was analyzed by using the Catastrophe Theory, and simulating analysis the rock pillar's stability of the huayingshan tunnel by using the FLAC3D software. the main conclusions of the study as follow:1) In the area near the excavation face ,the stress concentration was produced after the tunnel excavtion,. And becouse of this , the rock is easily became instability in the area near the excavation face, Therefore, as the tunnel excavating, the rock pillar becoming thin, this may cause the rock pillar Instability.2) In this paper, the stability of the rock pillar between the coal seam and excavation face was analyzed by using the Catastrophe Theory, got the result that, When the elastic modulus and the length of rock is smaller , the height of excavation face and vertical stress is greater, the system is more easily become instability.3) in this paper, the rock pillar's stability of the huayingshan tunnel was analyzed by using the FLAC3D software. The results show that, the plastic zone of the surround rock mainly concentrated at the bottom and dome area of the tunnel, the plastic zone of the rock pillar mainly concentrated at the area near the excavation face, and also got the result that, as the thickness of the rock pillar became thinner, the plastic zone is larger ,and the minimum thickness of the rock pillar of huayingshan tunnel should be 2.5m .