碩士 / 中原大學 / 土木工程研究所 / 86 / Dynamic compaction has been used in the field for many years as it possesses some advantages, e.g. low cost, to other types of soil improvement methods. This technique utilizes a tamper to fall from a distance above the ground surface so as to densify loose sands. Traditionally, the tamper has a flat bottom surface. A large portion of the compaction energy (67%) is carried by the surface waves that of no contributions to the densification of the sands. It is speculated that an improvement of the dynamic compaction technique may be obtained by modifying the bottom shape of the tamper so that a larger portion of the compaction energy is transmitted to the subsurface. This study utilized three tampers with different shape of bottom surfaces, i.e. flat, circular, and conical, to conduct a laboratory investigation on the effectiveness of dynamic compaction on densifying loose sands. Soil samples were taken from Mai-Liao reclaimed lands. Specimens of initial density of 40% were prepared by the air pluviation technique. The tampers had the same weight and diameter and were dropped from 30 and 60 cm high. Cone penetration tests were conducted before and after the dynamic compaction to verify the compaction effort. The sands were prepared in both dry and wet conditions. Results of this study show that shape of the bottom of the tamper affects slightly the cone penetration resistance of the improved sands. For the same compaction energy, the conical tamper creates the largest decrease in volume of the sands. The depth of the maximum improvement ratio, defined as change in cone resistance divided by initial cone resistance, is about 2-3 times of the diameter of the tamper.
| Identifer | oai:union.ndltd.org:TW/086CYCU0015013 |
| Date | January 1998 |
| Creators | SU YU TING, 蘇裕庭 |
| Contributors | Feng Dao Wei, 馮道偉 |
| Source Sets | National Digital Library of Theses and Dissertations in Taiwan |
| Language | zh-TW |
| Detected Language | English |
| Type | 學位論文 ; thesis |
| Format | 0 |
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