初始应力线和原状土的修正Mohr-Coulomb准则

发布时间：2018-08-31 16:33

【摘要】：原状土与重塑土在力学性质方面存在显著差别的原因,本质上在于建立在初始应力状态之上的结构性。重塑土一般是各向同性的,故在三维应力空间中其屈服曲面以等倾线为轴线。原状土由于在形成过程中一直处于三向不等压状态,故理论上讲其屈服曲面不能再以等倾线为轴线而应以初始应力线为轴线。该文以某真三轴试验为例,首先研究了特定八面体应变对应的广义剪应力随加载角的变化特征。随后,基于广义塑性力学和原状土的初始应力状态,提出了初始应力线的概念,并研究了初始应力线与等倾线的关系。进一步给出了三个适用于原状土的修正Mohr-Coulomb屈服准则,即平移模式、缩移模式和旋转模式。其中平移模式、缩移模式的屈服迹线仍然位于π平面上,而旋转模式的屈服迹线位于与初始应力线垂直的χ平面上。前两种模式可以通过等p真三轴试验结果直接对原状土的结构性进行评估;最后一种模式可以通过?1+K0?2+K0?3=c真三轴试验或等p真三轴试验数据在χ平面上的映射对原状土的结构性和各向异性进行研究。文献资料的验证表明,旋转模式修正Mohr-Coulomb屈服准则更能反映原状土的结构性,且物理意义清晰明确。
[Abstract]:The reason why there is significant difference in mechanical properties between undisturbed soil and remolded soil lies in the structure based on the initial stress state. The remolded soil is generally isotropic, so the yield surface of the remolded soil is on the axis of isoclinic in three dimensional stress space. Because the undisturbed soil has been in the state of three direction unequal compression during the forming process, theoretically speaking, the yield surface of the undisturbed soil can no longer be regarded as the axis of equitilting line, but with the initial stress line as the axis. Taking a true triaxial test as an example, the variation characteristics of generalized shear stress corresponding to a specific octahedron strain with the loading angle are studied in this paper. Then, based on the generalized plastic mechanics and the initial stress state of the undisturbed soil, the concept of the initial stress line is proposed, and the relationship between the initial stress line and the isoclinic line is studied. Furthermore, three modified Mohr-Coulomb yield criteria for undisturbed soils, i.e., translation mode, shrinkage mode and rotation mode, are presented. In the translation mode, the yield trace line of the contraction mode is still located on the 蟺 plane, while the yield trace line of the rotation mode is located on the 蠂 plane perpendicular to the initial stress line. The former two models can be used to evaluate the structure of undisturbed soil directly through the results of iso-true triaxial test. The last model can be used to study the structure and anisotropy of the undisturbed soil by mapping the true triaxial test data of 1 K0 / 2 K0 / 3 / c or equip triaxial test data on the 蠂 plane. The results show that the modified Mohr-Coulomb yield criterion can better reflect the structure of the undisturbed soil and the physical meaning is clear and clear.
【作者单位】：天津城建大学土木工程学院;天津市软土特性与工程环境重点实验室;新乡学院土木工程与建筑系;
【基金】：国家自然科学基金项目(41472253) 天津市自然科学基金重点项目(16JCZDJC39000)
【分类号】：TU411.7

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