Abstract:The axisymmetric characteristics line theory for weight materials was established based on the triple shear unified yield criterion. The main features are as follows: in describing the yield properties for materials under axisymmetric three dimensional stress states, the triple shear unified yield criterion used here can reflect the intermediate principal stress effects on the yield characteristics for materials compared with the Mohr-Coulomb yield criterion used before, and can be suitable to more kinds of materials because the common used criteria such as the Mohr-Coulomb failure criterion, the Tresca yield criterion and the Von Mises yield criterion can be expressed accurately with its only one equation. In describing the stress states in plastic zone, the Haar-Von Karman plasticity hypothesis based on the Mohr-Coulomb yield criterion is neglected through introducing the intermediate principal stress parameter to express the different stress states in plastic zones for different materials. This method can also take the Haar-Von Karman plasticity hypothesis as one of its special cases. As an example, pressures acting on the shaft wall were researched using the new axisymmetric characteristics line theory and results were compared with the traditional method. The results show that the proposed method gives a better description to the pressures acting on shafts influenced by yield properties for rock and/or soil round the shafts and the stress states in plastic zones.

Key words: triple shear unified yield criterion; unified axisymmetric characteristics line theory; pressure acting on shaft wall