(1. School of Civil Engineering, Chang'an University，Xi'an，Shaanxi 710061，China；2. Shanghai No.1 Municipal Engineering Co. Ltd.，Shanghai 200083，China；3. Key Laboratory of Geotechnical and Underground Engineering of Ministry of Education，Tongji University，Shanghai 200092，China；4. Department of Geotechnical Engineering，Tongji University，Shanghai 200092，China)
Abstract：Based on the unified strength theory and the elastic-brittle-plastic model，the new plastic solution for displacement of deep circular tunnels in rock is deduced. The influence of the elastic modulus variation in the plastic zone，intermediate principal stress，rock softening and shear dilation is all involved in this new formula. The new displacement solution obtained in this paper has a broadly theoretical meaning. More reasonable choices could be made according to the actual engineering situations. By analyzing an engineering case，the tunnel displacement calculated with the radius-dependent Young?s modulus is between the upper and lower bounds，which reflects the distance changes of the tunnel excavation unloading affect and is more consistent with the true situation of tunnel deformation. The effects of the unified strength theory parameter and shear dilation characteristic parameter on the tunnel displacement in the plastic zone are discussed. It is shown that the intermediate principal stress，shear dilation and the elastic modulus in the plastic zone have a significant effect on the tunnel plastic displacement，in which these three aspects influence each other and work together.
2011, Vol. 30 
