一种适用于岩土的扩展强度及屈服准则

土壤材料是一种典型的摩擦型材料,然而天然岩石却具有一定的凝聚力,而金属材料则完全是凝聚型材料. 在分析三种典型的材料强度准则表达式基础上,即SMP,Lade-Duncan以及广义Von-Mises准则,通过利用应力张量的不变量表达形式,提出了一种扩展准则即VML准则,该准则能够分别退化为上述3种典型准则. 在偏平面上,新准则能够描述从曲边三角形到圆形在内的多种开口形态;在子午面上,采用幂函数作为破坏准则公式,能够描述静水压力对于强度特性影响的非线性性质. 而对于土壤的屈服性质,岩土材料具有典型的压剪耦合特性,因此,为了描述剪切与等方向压缩两种路径下的体积耦合现象,采用水滴型屈服面作为屈服准则. 对于偏平面上的截面形状,讨论了给定球应力下偏应力强度值的分布形式及特点,讨论了应力罗德角对于偏平面上强度曲线的凹凸性的影响. 最后,通过多种材料的破坏与屈服试验成果,用所提新准则进行了验证. 通过强度以及屈服特性测试对比,验证了所提VML准则的合理性. 

AN EXTENDED STRENGTH AND YIELD CRITERION FOR GEOMATERIALS1)

Soil is a kind of typical friction material, while natural rock have certain cohesive properties and metal is a kind of completely cohesive material. Based on the analysis of three typical material strength criterion expressions, namely SMP, Lade-Duncan and Extended Von-Mises criterion, an extended criterion, VML criterion, is proposed by using the invariant expression of stress tensor, which can be degraded to the above three typical criteria respectively. In the deviatoric plane, the new criterion can be adopted to describe a variety of opening forms from curved triangle to circle, and in the meridian plane, the power function is adopted as the failure criterion formula, which can be used to describe the nonlinear property of the influence of hydrostatic pressure on the strength characteristics. As for the yield behavior of soil, geomaterials have typical compression-shear coupling characteristics. Therefore, in order to describe the volumetric coupling phenomenon under the two paths of shear and isotropic compression conditions, the droplet yield surface is adopted as the yield criterion. For the section shape on the deviatoric plane, the distribution and characteristics of the strength curve in the deviatoric plane with a fixed hydrostatic stress are discussed, and the influence of the stress Lode angle on the concavity and convexity of the strength curve in the deviatoric plane is discussed. Finally, the new criterion is used to verify the failure and yield test results of various materials. The comparison between prediction and test results have been employed. The comparison results have demonstrated the rationality of the proposed VML criterion.