| 刘嘉英,马刚,周伟,常晓林.基于离散元的颗粒材料三维临界状态与剪胀特性研究[J].水利学报,2017,48(9):1107-1117,1125 |
| 基于离散元的颗粒材料三维临界状态与剪胀特性研究 |
| Three-dimensional critical state and dilatancy of granular materials based on DEM |
| 投稿时间：2016-06-19 |
| DOI：10.13243/j.cnki.slxb.20160639 |
| 中文关键词: 颗粒材料 真三轴试验 离散元 临界状态 剪胀性 状态参量 |
| 英文关键词: granular materials true triaxial test DEM critical state dilatancy state parameter |
| 基金项目: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） |
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| 中文摘要: |
| 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。 |
| 英文摘要: |
| As an important part of classical soil mechanics,the critical state is always regarded as a refer-ent state in the foundation of the constitutive model of the granular materials, such as sandy soil. Accord-ing to the microscopic structure of sandy soils, the state parameter was proposed to describe the internal structure of sand, and series of state-dependent dilatancy theory were established. However, owing to the limitation of the experimental condition, researches of granular materials' critical state and dilatancy are usually investigated by the conventional triaxial tests, without the consideration of the intermediate principle stress. Researches have shown that the loading path have some effects on the mechanical response of granu-lar materials. In this paper, true triaxial tests are conducted using Discrete Element Method (DEM), the stress-strain behaviors are analyzed during the loading process,and the influence of the intermediate princi-ple stress ratio on the critical state is shown. The critical state line is unique in the e-log p plane,irrele-vant with the intermediate principal stress ratio. A three-dimensional state-dependent dilatancy equation is suggested by introducing the shape function. The relationship of the critical stress ratio and the Lode angle can be approximately described by a shape function. The numerical simulations show that the proposed three-dimensional equation can reflect the dilatancy behaviors of granular materials under complex loading paths,however it needs more verification of laboratory tests and theories. |
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