An exploratory discussion is presented on the application of egg-shaped function in elasto-plastic constitutive analysis for soft clay.Two main tasks of the paper are:1)to propose a complete yield criterion based on e...An exploratory discussion is presented on the application of egg-shaped function in elasto-plastic constitutive analysis for soft clay.Two main tasks of the paper are:1)to propose a complete yield criterion based on egg-shaped function and supplement its definition in the deviatoric section,and then a yield criterion suitable for 3D stress conditions is obtained;2)to elaborate its numerical implementation based on the drained triaxial tests.During the above discussion,a non-associated flow rule is proposed,in which the stress-dilatancy relationship in most classical theory is replaced by a linear dependence between the stress state parameterηand the rotation angleγof the plastic potential surface.Thereafter,isotropic and kinematic hardening behavior is considered by employing the hardening parameter H,which can be expressed as the function of plastic work Wp.Finally,comparisons between numerical results and test data on Taizhou soft clay are made to verify the effectiveness of the proposed model.展开更多
On the basis of upper bound theorem, non-associated flow rule and non-linear failure criterion were considered together.The modified shear strength parameters of materials were obtained with the help of the tangent me...On the basis of upper bound theorem, non-associated flow rule and non-linear failure criterion were considered together.The modified shear strength parameters of materials were obtained with the help of the tangent method. Employing the virtual power principle and strength reduction technique, the effects of dilatancy of materials, non-linear failure criterion, pore water pressure,surface loads and buried depth, on the stability of shallow tunnel were studied. In order to validate the effectiveness of the proposed approach, the solutions in the present work agree well with the existing results when the non-associated flow rule is reduced to the associated flow rule and the non-linear failure criterion is degenerated to the linear failure criterion. Compared with dilatancy of materials, the non-linear failure criterion exerts greater impact on the stability of shallow tunnels. The safety factor of shallow tunnels decreases and the failure surface expands outward when the dilatancy coefficient decreases. While the increase of nonlinear coefficient, the pore water pressure coefficient, the surface load and the buried depth results in the small safety factor. Therefore, the dilatancy as well as non-linear failure criterion should be taken into account in the design of shallow tunnel supporting structure. The supporting structure must be reinforced promptly to prevent potential mud from gushing or collapse accident in the areas with abundant pore water, large surface load or buried depth.展开更多
基金Project(41672264)supported by the National Natural Science Foundation of ChinaProject(2019C03103)supported by the Key Research and Development Program of Zhejiang Province,China。
文摘An exploratory discussion is presented on the application of egg-shaped function in elasto-plastic constitutive analysis for soft clay.Two main tasks of the paper are:1)to propose a complete yield criterion based on egg-shaped function and supplement its definition in the deviatoric section,and then a yield criterion suitable for 3D stress conditions is obtained;2)to elaborate its numerical implementation based on the drained triaxial tests.During the above discussion,a non-associated flow rule is proposed,in which the stress-dilatancy relationship in most classical theory is replaced by a linear dependence between the stress state parameterηand the rotation angleγof the plastic potential surface.Thereafter,isotropic and kinematic hardening behavior is considered by employing the hardening parameter H,which can be expressed as the function of plastic work Wp.Finally,comparisons between numerical results and test data on Taizhou soft clay are made to verify the effectiveness of the proposed model.
基金Project(2013CB036004) supported by the National Basic Research Program of ChinaProjects(51178468,51378510) supported by the National Natural Science Foundation of ChinaProject(CX2013B077) supported by Hunan Provincial Innovation Foundation for Postgraduate,China
文摘On the basis of upper bound theorem, non-associated flow rule and non-linear failure criterion were considered together.The modified shear strength parameters of materials were obtained with the help of the tangent method. Employing the virtual power principle and strength reduction technique, the effects of dilatancy of materials, non-linear failure criterion, pore water pressure,surface loads and buried depth, on the stability of shallow tunnel were studied. In order to validate the effectiveness of the proposed approach, the solutions in the present work agree well with the existing results when the non-associated flow rule is reduced to the associated flow rule and the non-linear failure criterion is degenerated to the linear failure criterion. Compared with dilatancy of materials, the non-linear failure criterion exerts greater impact on the stability of shallow tunnels. The safety factor of shallow tunnels decreases and the failure surface expands outward when the dilatancy coefficient decreases. While the increase of nonlinear coefficient, the pore water pressure coefficient, the surface load and the buried depth results in the small safety factor. Therefore, the dilatancy as well as non-linear failure criterion should be taken into account in the design of shallow tunnel supporting structure. The supporting structure must be reinforced promptly to prevent potential mud from gushing or collapse accident in the areas with abundant pore water, large surface load or buried depth.
