基于离散元的颗粒材料三维临界状态与剪胀特性研究

发布时间：2018-06-07 17:34

本文选题：颗粒材料 + 真三轴试验　；参考：《水利学报》2017年09期

【摘要】：临界状态通常作为砂土等颗粒材料本构模型中的一种参考状态,是经典土力学框架的一个重要组成部分。根据砂土的细观结构特性,一些学者提出了描述砂土内部结构特性的状态参量,建立了状态相关的剪胀模型。然而受试验条件的限制,目前多采用常规三轴试验研究颗粒材料的临界状态和剪胀特性,未考虑中主应力因素。已有研究表明加载路径对颗粒材料的力学特性有一定影响,本文采用离散单元法模拟了颗粒材料真三轴应力路径试验,分析了加载过程中颗粒材料的应力应变特性及中主应力对临界状态的影响。结果表明:颗粒材料的临界状态线(CSL)在e-lg p平面内是唯一的,与中主应力系数无关。临界状态应力比与应力罗德角的关系可以采用角隅函数近似表达。基于状态相关的剪胀理论,采用Lode角的函数(角隅函数)表示模型参数,提出一个新的应力-剪胀模型。数值试验结果表明,本文采用的三维剪胀模型能够较好地反映了离散元数值模拟中颗粒材料在三维应力路径下的剪胀特性,然而公式的适用性需要更多的试验验证和理论研究。
[Abstract]:The critical state is usually used as a reference state in the constitutive model of granular materials such as sand. It is an important part of the classical soil mechanics frame. According to the meso-structure characteristics of sand, some scholars put forward the state parameters to describe the internal structural characteristics of sand, and established a state dependent shear expansion model. However, due to the limitation of test conditions, conventional triaxial tests are often used to study the critical state and shear dilatancy of granular materials without considering the medium principal stress factors. It has been shown that the loading path has a certain influence on the mechanical properties of the granular material. In this paper, the true triaxial stress path test of the granular material is simulated by using the discrete element method. The stress-strain characteristics of granular materials during loading and the effect of intermediate principal stress on critical state are analyzed. The results show that the critical state line of granular material is unique in the e-lg p plane and independent of the intermediate principal stress coefficient. The relation between critical stress ratio and stress Luo De angle can be expressed by corner function. Based on the state-dependent theory of shear expansion, a new stress-shear expansion model is proposed by using the function of Lode angle (corner function) to represent the parameters of the model. The results of numerical experiments show that the three-dimensional dilatancy model in this paper can well reflect the dilatancy characteristics of granular materials under three-dimensional stress paths in discrete element numerical simulation. However, the applicability of the formula needs more experimental verification and theoretical research.
【作者单位】：武汉大学水资源与水电工程科学国家重点实验室;水工岩石力学教育部重点实验室;
【基金】：国家自然科学基金面上项目(51579193);国家自然科学基金青年基金项目(51509190) 中国博士后科学基金面上项目(2016T907272)
【分类号】：TV223

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