Study on the creep test of cemented sand

• Main Authors: Jin-Yi Yu, 游瑾宜
• Other Authors: Kuang-Tsung Chang
• Format: Others
• Language: zh-TW
• Published: 2019
• Online Access: http://ndltd.ncl.edu.tw/cgi-bin/gs32/gsweb.cgi/login?o=dnclcdr&s=id=%22107NCHU5080032%22.&searchmode=basic

碩士 === 國立中興大學 === 水土保持學系所 === 107 === Using triaxial tests, before the failure of specimens, the deviator stress was fixed and the cyclic mean stress was applied to study the influence of creep on cemented sand. Compared with the natural geological materials with anisotropy, cemented sand is a synthetic material with homogeneous and uniform advantages, so the error caused by the test is small. Due to the material composition, cemented sand has the property of being weakened by water, so the pore water pressure is not added during the test. It has been found through experiments that the creep test with the cyclic mean stress has a shorter duration than the conventional creep test with only fixed deviator stress, and the volumetric strain of the two creep test is similar. Therefore, in order to shorten the time of observing the material''s creep behavior, a creep test method with a fixed deviator stress and cyclic mean stress is selected for research. The test results show that the axial strain accumulation, the axial strain rate, and the strength after creep of cemented sand, both are positively correlated with the creep initial mean stress, under the same creep time and creep initial stress ratio. The test results also show that the axial strain accumulation and the axial strain rate of cemented sand are positively correlated with the creep initial stress ratio, and the strength after creep of cemented sand is negatively correlated with the creep initial stress ratio, under the same creep time and creep initial mean stress. Under the same creep initial stress ratio, cemented sand with the same amplitude and period for triaxial creep test. According to the test results, the number of cycles to failure, the axial strain accumulation and the axial strain rate in the creep second stage of cemented sand are positively correlated with the creep initial mean stress. In this study, cemented sand was used to conduct the creep test. After testing, it was found that the volumetric strain case of the cyclic mean stress creep test is similar to the conventional creep test with only fixed deviator stress and is relatively short. Therefore, the cyclic creep test may be used to replace the traditional creep test to shorten the time for studying the material''s creep behavior. Although the creep behavior discussed in this study is not quite comprehensive due to the limitations of measuring instruments., it may be a possibility to replace the traditional creep test with a cyclic creep test. In addition, it is also observed that the creep initial stress ratio, and the creep initial mean stress both have an effect on the creep behavior of the cemented sand.