考虑主应力轴旋转作用的一个增量模型

发布时间：2018-05-15 22:01

本文选题：土力学 + 单剪　；参考：《岩石力学与工程学报》2017年09期

【摘要】：为了探究主应力轴旋转作用下土体的变形规律,采用如下思路构建模型:(1)分析二维铝棒的单剪试验结果可知,剪应力与正应力之比(剪应力比)与剪应变的类似双曲线关系,采用威布尔函数作为描述上述二者的关系表达式,不仅可反映双曲线型关系,还能充分考虑到应力比的应变软化现象。(2)利用应力莫尔圆上的应力比表达式,与威布尔函数联立得到了剪应变的隐函数。该隐函数认为有3个影响剪应变的因素:反映等向压缩或偏压作用下产生剪应变的球应力p,对于一般剪切作用下产生相应剪应变的滑动摩擦角φm,在莫尔圆上剪应力与大主应力之间的夹角半角a。(3)通过对上述隐函数求导可得到剪应变与剪应力比之间的增量表达式,联立Rowe剪胀方程,建立二维条件下的考虑主应力轴旋转的增量本构模型,上述二维方程可通过SMP准则拓展为三维增量本构模型。所提WB模型不仅能反映土体的压硬性、剪切体缩、体胀、应变硬化、软化,还能充分反映主应力轴旋转作用下的土体一般应力应变关系。通过莫尔圆圆周应力路径以及单剪试验和等向压缩试验的结果与预测结果对比,验证了所提模型的适用性及合理性。
[Abstract]:In order to investigate the deformation law of soil under the rotation of principal stress axis, the following train of thought was used to construct the model: 1) to analyze the single shear test results of two-dimensional aluminum bars. The results show that the ratio of shear stress to normal stress (the ratio of shear stress to normal stress) and shear strain are similar hyperbolic relations. Using Weibull function as the expression to describe the above two relations can not only reflect the hyperbolic relation, but also fully consider the strain softening phenomenon of stress ratio. In conjunction with Weibull function, the implicit function of shear strain is obtained. The implicit function holds that there are three factors influencing the shear strain: the spherical stress p, which reflects the shear strain under isotropic compression or biasing, and the sliding friction angle 蠁 m, which produces the corresponding shear strain under the general shear action, and shearing on the moire circle. The increment expression between shear strain and shear stress ratio can be obtained by the derivation of the implicit function. An incremental constitutive model considering the rotation of principal stress axis is established under two-dimensional condition by simultaneous Rowe shear expansion equation. The above two-dimensional equations can be extended to a three-dimensional incremental constitutive model by means of SMP criterion. The proposed WB model can not only reflect the compressive stiffness, shearing shrinkage, bulging, strain hardening and softening of soil, but also fully reflect the general stress-strain relationship of soil under the rotation of principal stress axis. The applicability and reasonableness of the proposed model are verified by comparing the results of the moire circular stress path and the single shear test and the isotropic compression test with the predicted results.
【作者单位】：中国建筑科学研究院地基基础研究所;
【基金】：国家自然科学青年基金项目(11402260) 中国建筑科学研究院应用技术研究基金项目(20141602330730038) 住建部科技计划研究基金项目(20161602420730011)~~
【分类号】：TU43

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