二维粒状材料双轴压缩试验系统的研制与应用

为研究粒状材料的力学特性及其与材料细观组构演化之间的关系,新研制了一套适用于粒状材料的二维双轴压缩试验系统,并以金属棒等模拟材料组成的二维堆积体为试验对象,在水平和竖直两个方向独立加载,能实现常侧向压力、等p和等应力比等多种应力路径。采用数字照相结合图像相关分析技术高精度地实现了对材料细观组构的跟踪测量,并可分析二维粒状材料内部的应变局部化及细观组构的演化过程。使用该双轴压缩试验系统,针对椭圆形截面金属棒组成的二维粒状材料试样进行了常侧向压力的压缩试验,验证了该试验系统的有效性。

Development and application of a 2D biaxial compression test system for granular materials

A set of two-dimensional biaxial compression test system was developed to investigate the stress-strain behavior and its variation with the micro-fabric for granular materials.During testing a specimen was assembled using very small metal bars with elliptical sectional shapes and then was loaded in both horizontal and vertical directions.Three different stress paths,including constant lateral pressure,constant mean principal stress and constant principal stress ratio,could be easily realized.A new method of non-invasive measurement using both digital photo technology and image correlation analysis was developed so that the displacement of each metal bar in the specimen could be truly traced and as a result the displacement field of each specimen and its micro-fabric evolution during application of loading could be measured with a high degree of accuracy.The new test system was applied in monotonic shear tests for two-dimensional assemblies of mental bars with different elliptical sections,showing its essential effectiveness for the investigation of the micro-fabric variation and mechanical behavior.