Engineering Research Equipment Grant: Closed-Loop Cyclic Triaxial Testing System for Earthquake Engineering Research

新罕布什尔大学开发了一种声学系统，能够对土壤样品进行精确的剪切波和压缩波速度测量。该系统已用于确定砂土中声波传输特性与液化阻力的关系。本项目的目的是对现有的循环三轴加载装置进行升级，提高声学系统的运行速度。目的是确定该系统在动态加载下研究粘土行为的能力，具体如下：(1)各加载周期残余孔隙水压力的产生及孔隙压力变化；(2)剪切模量退化与循环剪切应变阈值水平；(3)材料阻尼随循环应变水平的演化。这种新的测试系统有可能在地震期间由于土壤液化现象而导致的地球质量和建筑基础的破坏方面产生重要信息。

An acoustic system capable of making accurate shear and compression-wave velocity measurements in soil specimens has been developed at the University of New Hampshire. This system has been used to determine the relationship between acoustic wave transmission characteristics and liquefaction resistance in sands. The objective of this project is to upgrade an existing cyclic triaxial soil loading device, and to increase the speed of operation of the acoustic system. The aim is to determine the capability of this system to investigate the behavior of clays under dynamic loading, specifically: (1) The generation of residual pore-water pressures and pore-pressure variation during individual loading cycles; (2) Shear modulus degradation and threshold levels of cyclic shear strain; (3) Evolution of material damping with cyclic strain level. This new testing system has the potential to yield important information on the failure of earth masses and building foundations during earthquakes due to the phenomenon of soil liquefaction.