Investigation of Post Cyclic Behavior of Sands under The Framework of Binary Packing

• Main Authors: Ya-Ru Li, 李亞儒
• Other Authors: Louis Ge
• Format: Others
• Language: en_US
• Published: 2019
• Online Access: http://ndltd.ncl.edu.tw/handle/9z2r2c

碩士 === 國立臺灣大學 === 土木工程學研究所 === 107 === Taiwan is located on the circum-pacific seismic belt, where more than 16 thousand earthquakes along with liquefaction occurs each year. Liquefaction may make the buildings tilted and induce ground settlement. In-situ soils are composed by various sizes and different types of particles. The arrangements may change the behavior of the mixtures. The previous experimental result shows fines content equals to 35% is a limit value (the densest condition). Based on the framework of binary packing, those two proportions both locate on the left side To observe the post-cyclic behavior of the granular mixtures, this research uses different proportions of fine sands by weight to conduct three types of triaxial tests, which include CID, CIU, and CIUcyc tests. All the specimens are prepared by wet tamping method. The result shows that, the reduction of the soil strength is not a decrement trend when ru value increases at the fines content equals to 35% (ru = 0.5 is a critical point). While the ru value is approximately less than 0.5, the deviatoric stress at monotonic loading becomes lower with the more excess pore water pressure is generated in cyclic loading. But, the ru value exceeds the 0.5 approximately, the soil strength of specimen becomes greater when the excess pore water pressure becomes higher. In addition, there is a different performance for the specimens with fines content equals to 15%. The result shows a huge decreased phenomenon of the soil strength when the ru goes beyond 0.45. Furthermore, the soil strength exhibits the similar value when the ru value goes below 0.45. This research also points out the diversification of the axial strain during the cyclic loading is a main reason to occur this kind of result. The intergranular void ratio is considered a better parameter to describe the actual contact condition of the coarse and fine particle in granular mixture.