Laboratory study of anisotropic behavior of compacted soil

• Main Authors: Wang, Ying-Yu, 王瀅郁
• Other Authors: Lin, Chih-Ping
• Format: Others
• Language: zh-TW
• Published: 2013
• Online Access: http://ndltd.ncl.edu.tw/handle/60776247816687626069

碩士 === 國立交通大學 === 土木工程系所 === 101 === In order to increase the efficiency of quality control and assurance, several non-nuclear testing technologies have been under development in recent years. Liu (2010) applied shear wave velocity measurement for such a purpose. However, his results show that there is a significant difference between the shear wave velocities obtained in-situ by the multichannel analysis of surface wave and that obtained from bender element system in the laboratory. Compaction energy and compaction techniques may play roles in the difference. The anisotropy of the compacted soil is probably another one. However, the degree of anisotropy in compacted soil and the effect of anisotropy on wave velocities are not known. Thus, the aim of this study is to investigate the anisotropic behavior of compacted soil by laboratory experiments. A bender-extender element system was established to measure both the compression and shear wave velocity in compacted soils. Several details on assembling of the testing system were discussed and optimized. A multi-angle measurement device was designed to measure the elastic wave velocity in different angle relative to the symmetric axis of the compacted soil sample. According to the experimental results, on the wet side, the shear wave velocity parallel to the symmetric axis keeps decreasing while water content increase. On the contrary, the shear wave velocity on the dry side fluctuates as water content decreases. Furthermore, observation from the anisotropy factors reveals that the anisotropy becomes more obvious (greater or smaller than one) when water content is close to or greater than the optimum water content. Further studies worth to be conducted were suggested.