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剪胀是岩土材料一个非常重要的特性,但目前对于剪胀的描述并不统一。剪胀角在滑移线场理论中主要有两种定义:①是实际塑性应变ε与剪切应变γ之间的夹角;②是破坏面(应力滑移线)与速度矢量方向的夹角(此时也称膨胀角)。在有限元计算中剪胀角则通过塑性势函数来定义,但对塑性势函数的选择比较随意,只是将屈服函数中的内摩擦角换成剪胀角,此时的剪胀角已没有明显的物理意义,只能在一定程度上反映材料的剪胀特性。阐明了滑移线场理论中有关剪胀的描述,推导了平面应变条件下考虑剪胀角影响并与Mohr-Coulomb准则精确匹配的广义Mises准则,研究了剪胀对浅基破坏模式的影响。
Dilatancy is a very important feature of geomaterials, but the current description of dilatancy is not uniform. There are two main definitions of dilatancy angle in the theory of slip line field: ① is the angle between the actual plastic strain ε and the shear strain γ; ② is the angle between the sabotage plane (stress slip line) and the direction of the velocity vector (Also known as expansion angle). In the finite element calculation, the dilatancy angle is defined by the plastic potential function. However, the selection of the plastic potential function is relatively arbitrary, but the internal friction angle in the yield function is replaced by the dilatancy angle. At this time, the dilatancy angle is not obvious The physical meaning, only to some extent, reflect the dilatancy characteristics of the material. The description of dilatancy in slip field theory is expounded. The generalized Mises criterion considering the effect of dilatancy angle under plane strain condition and exact matching with Mohr-Coulomb criterion is derived, and the influence of dilatancy on the failure mode of shallow foundation is studied.