In this paper, the asymmetric laminar flow in a porous channel with expanding or contracting walls is investigated. The governing equations are reduced to ordinary ones by using suitable similar transformations. Homot...In this paper, the asymmetric laminar flow in a porous channel with expanding or contracting walls is investigated. The governing equations are reduced to ordinary ones by using suitable similar transformations. Homotopy analysis method （HAM） is employed to obtain the expres- sions for velocity fields. Graphs are sketched for values of parameters and associated dynamic characteristics, especially the expansion ratio, are analyzed in detail.展开更多
To provide precise prediction of tunnelling-induced deformation of the surrounding geomaterials,a framework for derivation of rigorous large-strain solutions of unified spherical and cylindrical cavity contraction is ...To provide precise prediction of tunnelling-induced deformation of the surrounding geomaterials,a framework for derivation of rigorous large-strain solutions of unified spherical and cylindrical cavity contraction is presented for description of confinement-convergence responses for deep tunnels in geomaterials.Considering the tunnelling-induced large deformation,logarithmic strains are adopted for cavity contraction analyses in linearly elastic,non-associated Mohr-Coulomb,and brittle Hoek-Brown media.Compared with approximate solutions,the approximation error indicates the importance of release of small-strain restrictions for estimating tunnel convergence profiles,especially in terms of the scenarios with high stress condition and stiffness degradation under large deformation.The ground reaction curve is therefore predicted to describe the volume loss and stress relaxation around the tunnel walls.The stiffness of circular lining is calculated from the geometry and equivalent modulus of the supporting structure,and a lining installation factor is thus introduced to indicate the time of lining installation based on the prediction of spherical cavity contraction around the tunnel opening face.This study also provides a general approach for solutions using other sophisticated geomaterial models,and serves as benchmarks for analytical developments in consideration of nonlinear large-deformation behaviour and for numerical analyses of underground excavation.展开更多
基金supported by the National Natural Science Foundations of China (50936003, 50905013)The Open Project of State Key Lab. for Adv. Matals and Materials (2009Z-02)Research Foundation of Engineering Research Institute of USTB
文摘In this paper, the asymmetric laminar flow in a porous channel with expanding or contracting walls is investigated. The governing equations are reduced to ordinary ones by using suitable similar transformations. Homotopy analysis method （HAM） is employed to obtain the expres- sions for velocity fields. Graphs are sketched for values of parameters and associated dynamic characteristics, especially the expansion ratio, are analyzed in detail.
基金financial supports from the Foundation of Key Laboratory of Transportation Tunnel Engineering(Southwest Jiaotong University)Ministry of Education,China(Grant No.TTE2017-04)+1 种基金National Natural Science Foundation of China(Grant No.51908546)Natural Science Foundation of Jiangsu Province(Grant No.BK20170279)。
文摘To provide precise prediction of tunnelling-induced deformation of the surrounding geomaterials,a framework for derivation of rigorous large-strain solutions of unified spherical and cylindrical cavity contraction is presented for description of confinement-convergence responses for deep tunnels in geomaterials.Considering the tunnelling-induced large deformation,logarithmic strains are adopted for cavity contraction analyses in linearly elastic,non-associated Mohr-Coulomb,and brittle Hoek-Brown media.Compared with approximate solutions,the approximation error indicates the importance of release of small-strain restrictions for estimating tunnel convergence profiles,especially in terms of the scenarios with high stress condition and stiffness degradation under large deformation.The ground reaction curve is therefore predicted to describe the volume loss and stress relaxation around the tunnel walls.The stiffness of circular lining is calculated from the geometry and equivalent modulus of the supporting structure,and a lining installation factor is thus introduced to indicate the time of lining installation based on the prediction of spherical cavity contraction around the tunnel opening face.This study also provides a general approach for solutions using other sophisticated geomaterial models,and serves as benchmarks for analytical developments in consideration of nonlinear large-deformation behaviour and for numerical analyses of underground excavation.
