Research On Support Technology For Highly-stressed Tunnels At Depth

As a kind of important underground structure, tunnel is very useful at many fields such as the traffic, coal mining and water conservancy. With the construction of high-grade highway tunnel, railway tunnel and hydraulic tunnel, a lot of experiences on tunnel support are accumulated, which results in the advancement of tunnel support technology. However for high stress deep tunnel, support appears complicated problems, which increases the support difficulty and cost, besides, its natural safe hidden trouble such as rock-burst, large deformation cannot avoid. According to the summary of rock-burst's prevention method during deep tunnel construction stage and rock-burst's appearance theory at home and abroad ,this paper improves the support plan of deep tunnel under the condition of rock-burst: primary lining uses bolts and shotcrete, secondary lining uses mold casting concrete, which for that improving the support effectiveness and ensuring the construction safe has some theoretical and application value.Deep tunnel crosses the high ground stress area, tunnel excavation will lead to local ground stress sudden release and redistribution around tunnel, which forming high secondary ground stress, when secondary ground stress increase to some level, part of tunnel will appear rock-burst, it brings up hidden trouble to tunnel construction. This paper focuses on the stability of tunnel which under many load and the tunnel support plan.Finally, under the background of a tunnel crossing high ground stress grade 3 surrounding rock, based on the conditions of using steel fiber reinforced shotcrete and using plain shotcrete, uses software FLAC3D to calculate and analyze the lining stress field, surrounding rock strain field, The obtained two groups of data is compared. According to many times selections and calculation of thickness of steel fiber reinforced shotcrete and plain shotcrete, it proves that steel fiber reinforced shotcrete better than plain shotcrete on support effect. So steel fiber reinforced shotcrete should be the first choice for tunnel support on the condition of tunnel crossing high ground stress and having rock-burst tendency.