Interpretation of mechanical behavior of frozen clay through parallel tests of frozen and unfrozen soils
Interpretation of mechanical behavior of frozen clay through parallel tests of frozen and unfrozen soils
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DOI：
10.3208/jgssp.v05.042
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发表时间：
2017-02
期刊：
影响因子：
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通讯作者：
Jin-Yen Wang;S. Nishimura
中科院分区：
文献类型：
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作者：
Jin-Yen Wang;S. Nishimura
本研究报告了一个基本的实验项目，旨在提出一种方法来开发一个描述性框架，将有效应力和粘塑性的概念扩展到冻结状态。在不同温度（低于冻结温度3个，高于冻结温度1个）和应变速率下，对重塑Kasaoka粘土进行了三轴压缩试验。冻结前各向同性固结至100、200或400kPa，待试验温度稳定后分别以恒定应变速率10 - 3,10 -4和10 -5 min -1剪切试件。观察到的行为通过与未冻结试样的比较来解释，未冻结试样经历了与冻结试样相同的应变路径，通过固结和膨胀，对应于孔隙水相变引起的体积变化。冻结试样的强度，以及远远大于未冻结试样的强度，对应变速率的依赖性更大，这可能是由于冰的存在。根据Ladanyi和Morel（1990）关于同一土体冻结和未冻结状态下的应变路径和有效应力路径唯一相关的假设，通过精心控制的冻结和未冻结状态平行试验，探索冻土土骨架所遵循的“有效应力路径”。根据设想的有效应力路径，绘制了不同温度下的临界状态线（CSLs）。冻土区和非冻土区的上述特征有望导致建立一个描述两种状态行为的统一框架。
This study reports a fundamental experimental program that aims to propose an approach towards developing a descriptive framework that extends the concept of effective stress and viscoplasticity to frozen states. A series of triaxial compression tests was conducted on reconstituted Kasaoka Clay at different temperatures (three temperatures below the freezing temperature and one above it) and strain rates. The specimens were isotropically normally consolidated to 100, 200 or 400kPa before freezing and sheared at constant strain rates of 10 -3 , 10 -4 and 10 -5 min -1 after the test temperature got stabilized. The observed behavior was interpreted through comparisons with that of unfrozen specimens, which were subjected to a same strain path as that for the frozen specimens through consolidation and swelling corresponding to the volumetric changes due to pore water phase changes. The strength of frozen specimens, as well as being far larger than that of unfrozen specimens, showed much more significant dependence on the strain rate, which is probably due to the presence of the ice. In light of Ladanyi and Morel’s (1990) hypothesis on the uniquely related strain path and effective stress path of both frozen and unfrozen states of the same soils, the “effective stress paths” followed by the soil skeleton of the frozen soil were probed by the carefully controlled parallel tests on the frozen and unfrozen states. The Critical State Lines (CSLs) at different temperatures were thus plotted based on the envisaged effective stress paths. The above characterization of frozen and unfrozen soils is expected to lead to construction of a unified framework for describing the behaviors of both states.