Soil Strees-Strain Characteristics Using an Automated True Triaxial Testing Device

具有柔性边界的自动电-气控制真三轴试验装置，使学生能够研究应力路径和排水条件对土壤强度的重要性。已经开发了两种使用这种装置的实验室实验。第一课让学生熟悉与静态传感器校准、模数转换、信号调理、软件和硬件增益以及混叠问题相关的概念。第二种类型处理土样的各向同性和各向异性固结和测试，使用预定义的应力路径。应力和应变控制的静剪试验可以进行，基本上任何应力路径都可以通过数据采集和控制软件进行模拟。这种实验室能力表明，使用相同的测试设备，各种实验室强度测试与实际现场条件的相关性，并说明了与电子数据采集和控制相关的概念。一个重要的好处是，相同的装置可以用来说明排水和不排水应力-应变特性的各向同性和Ko固结土样品。样品可以在预定义的应力路径下剪切，并且可以比较观察到的孔隙压力行为（不排水测试）。开发了土壤测试程序来检查与固结类型，应力路径和加载速率相关的问题。

9452059 Penumadu An automated electro-pneumatic controlled true triaxial testing device with flexible boundaries enables students to investigate the importance of stress path and drainage conditions on the strength of soils. Two types of laboratory experiments that use this device have been developed. The first familiarizes students with concepts related to static transducer calibration, analog to digital conversion, signal conditioning, software and hardware gain and problems of aliasing. The second type deals with the isotropic and anisotropic consolidation and testing of soil samples using a predefined stress path. Stress and strain controlled static shear tests can be performed and essentially any stress path can be simulated through the data acquisition and control software. This laboratory capability shows the relevance of the various laboratory strength tests with actual field conditions using the same testing device, and illustrates the concepts related to electronic data acquisition and control. An important benefit is that the same device can be used to illustrate the drained and undrained stress-strain characteristics of both isotropic and Ko consolidated soil samples. The samples can be sheared under a predefined stress path and the observed pore pressure behavior (for undrained testing) can be compared. Soil testing programs are developed to examine the issues related to type of consolidation, stress path and the rate of loading.