粒状介质三维复杂应力加载离散元数值试验方法  

DEM numerical test method for granular matter under complex 3D loading

作　　者：薛龙 王睿[1,2] 张建民[1,2] XUE Long;WANG Rui;ZHANG Jian-min(Institute of Geotechnical Engineering,School of Clvil Engineering,Tsinghua Untversity,Beijing 100084,China;National Engineering Laboratory for Green &Safe Construction Technology in Urban Rail Transit,Tsinghua University,Beljlng 100084,China)

机构地区：[1]清华大学土木水利学院岩土工程研究所,北京100084 [2]清华大学城市轨道交通绿色与安全建造技术国家工程实验室,北京100084

出　　处：《岩土力学》2018年第12期4681-4690,共10页Rock and Soil Mechanics

基　　金：国家自然科学基金面上项目(No.51678346);国家重点研发计划项目(No.2016YFC1402800)~~

摘　　要：实际荷载条件下(如交通、地震荷载),粒状岩土材料常受到三维复杂应力路径作用。目前,多数粒状岩土材料的本构理论和模型都基于简单应力路径加载条件下的物理试验提出,在更加复杂应力路径下的适用性则需要进一步验证。但受机械控制的限制,物理试验中无法实现很多客观存在的三维复杂应力路径加载。为了能够再现并分析三维复杂应力路径下粒状介质的力学响应,提出了一种离散元数值试验方法,该方法采用球形数值试样,通过直接控制试样边界应力达到对3个主应力大小和方向的任意控制,从而可以实现诸多物理试验中无法实现的复杂应力路径。通过与目前常见的一些物理试验进行定性对比,论证了该数值试验方法通过高精度的加载控制和测量能够再现已有物理试验现象。在此基础上,进一步开展了应力主轴的三维旋转,分析了在这种实际存在却无法通过物理试验再现的加载条件下粒状介质的变形规律,初步显示了提出的数值试验方法在深入研究三维复杂应力路径下粒状介质力学响应方面所拥有的能力和优势。Under engineering loads such as traffic and seismic loads, granular soil is often subjected to complex 3 D stress paths. Most existing constitutive theories and models for granular soil have been proposed based on results from laboratory tests conducted under relatively simple loading conditions. Therefore, the existing constitutive theories and models need to be verified under more realistic stress paths if they are to be applied to engineering practice. However, due to limitations in mechanical control, conducting laboratory tests with complex 3 D loading is often very difficult or even impossible. In this study, a new numerical test method is proposed to provide the means to investigate the mechanical response of granular material under complex 3 D loading. Spherical numerical specimens are adopted along with high precision stress-controlled boundaries, allowing for the application of any arbitrary stress state, forming the basis for complex 3 D loading. Combined with a set of stress and strain measurement techniques, most existing physical tests can be quantitatively and numerically reproduced. Then, the 3 D rotation of principal stress axes is achieved, exhibiting the advantages to use this method in the investigation of the mechanical response of granular material under complex 3 D loading.

关 键 词：粒状介质 数值试验 离散元 三维复杂应力路径 

分 类 号：TU452[建筑科学—岩土工程]