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Abstract Based on the evident rheology characteristic of soft rock tunnel in high geostress zone，a new support scheme which adds U-steels compressible stent and foam concretes filling layer to the spray anchor network support is proposed. The long-term stability of Xiakou soft rock tunnel with high geostress in Yichang—Badong expressway is studied by using the new U-steel connector mechanical model and contact model between U-steel and surrounding rock in two support schemes. The results show that：(1) The relationship between the compression and friction resistance for U-steel support is well reflected by the built model consisting of U-steel connector mechanical model and contact model between U-steel and surrounding rock. (2) The combined support of U-steels compressible stent and foam concretes filling layer can absorb rheological deformation of surrounding rocks，which reduces the deformation pressure of the secondary lining； and also，it can provide stable supporting force，which is helpful to keep long-term stability for soft rock tunnel with high geostress.
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Received: 08 April 2011
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2011, Vol. 30 
