(1. Key Laboratory of Geotechnical and Underground Engineering of Ministry of Education,Tongji University,Shanghai 200092,China;2. Department of Geotechnical Engineering,Tongji University,Shanghai 200092,China)
Abstract:Firstly,taking use of the correspondence principle,the viscoelastic solution for the circular tunnel with constant ratio of stress release is obtained,based on the elastic solution of the circular tunnel under non-hydrostatic pressure. Then,the stress is released step by step during construction,and the boundary condition at the intrados will change along with the distance x between excavating face and the studred section. The distance x could be expressed as a function of excavation speed v and time t. so the boundary condition could be expressed as a function of time t and speed v. According to the Stieltjes integrals, the items of ?Fi(t)(i = 1–11) in the solution for constant ratio of stress release are replaced with the integrals of Fi(t) with respect to d?(t). The solution for the circular tunnel under non-hydrostatic pressure considering the ratio of stress release could be obtained. When the ratio of horizontal pressure coefficients k0 = 1,the solution could be transformed into the viscoelastic solution for the circular tunnel under hydrostatic pressure considering the ratio of stress release. When the ratio of stress release ? = 1,the solution will be transformed into the viscoelastic solution for the circular tunnel under non-hydrostatic pressure without considering the ratio of stress release. So the latter two solutions are special cases of the solution in the paper. The non-hydrostatic pressure assumption accords with the engineering practice,and the ratio of stress release indicates the effects of construction procedure on the stress and deformation of rock. The results could be a reference for the design and construction of tunnels.
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