未飽和土壤單向度壓縮性質之實驗研究

A Laboratory Study on the One-Dimensional Compression Properties of Unsaturated soils

陳育辰(Yu-Chen Chen)

指導教授 ： 馮道偉

中原大學/工學院/土木工程學系/碩士(2008年)

https://doi.org/10.6840/cycu200900234

摘要

中 文 摘 要

在地表附近的土壤多為複合土壤且為非飽和，在土體中包含水、空氣及礦物顆粒，其壓縮變形主要來自於水或空氣被擠出。此一過程並非瞬間完成，而是依據土壤性質而定，一般而言，黏土的壓縮速率極慢，砂土的壓縮速率極快，二者相差極多，但皆與時間有關。過去在研究土壤的壓縮性質之實驗上，常以傳統的飽和單向度壓密試驗評估壓密性質，且土壤試體大多為滲透性較低的細顆粒土壤，而忽略了粗顆粒土壤，如砂土和複合土壤，對於未飽和土壤之壓縮性質的研究也不多，現地在地下水位以上的土壤多被視為非飽和土壤，特別的情形如填海造地工程多以粗顆粒土壤進行回填，且其地表高程約在平均海平面之上4 m，可說是許多的回填砂土皆在未飽和狀態。
本研究以不同種類土壤，即高嶺土、渥太華砂、越南砂、麥寮砂與麥寮砂加入細料，來製作未飽和試體以進行單向度壓密試驗，並探討土壤之壓縮性。試驗結果顯示，高嶺土試樣之 / 比值約在0.014～0.02之間；砂土試體之壓縮指數與二次壓縮指數多隨壓密應力增大而增大，隨著飽和度增加而減少；麥寮砂試樣之壓縮指數與二次壓縮指數在低飽和度(S = 0%～20%)時，會有些許上升而後下降之情形。砂土試體之 / 比值在飽和度為0%時最低，在飽和度為100%時為最高，其比值約在0.01～0.035之間，麥寮砂試樣在低飽和度(S = 0%～20%)時，會有些許上升而後下降之情形。因此，砂土之飽和度對壓縮性質有所影響。

關鍵字

壓縮指數 ； 二次壓縮指數 ； 未飽和土壤

並列摘要

ABSTRACT
The soil near the surface of the earth almost are composite soil and unsaturated . The soil is composed of water, air and mineral particle . Soil compresses because of the water and air are squeezed. This process may not complete in a few second. That depends on soil property. Generally speaking, the compression rate of day is very slow and compression rate of sand is very fast.
In the past, the experiment of studying soil’s compression properties is usually by oedometers. The specimen usually is fine-grained soil which is low in permeability. Coarse-grained soil such as sand and composite soils is usually ignored. The study of unsaturated soil compression properties is also not much. The soil above the groundwater level is regarded as unsaturated soils. Hydraulic rcelamation uses coarse-grained soil and the ground elevation is above sea leve around 4m. where reclaimed sand may be unsaturated.
This study use kaolin、Ottawa sand、Vietnam sand、Mai-Liao sand and Mai-Liao sand with differect fine conteats aggregate to make unsaturated oedometer specimens. The results show that the ratio of / of kaolinite specimen is around 0.014～0.02. Compression index and secondary compression index of the specimens almost increase with consolidation pressure and decreace with increasing in saturation. There is a situation of rising then drop for the compression index and secondary compression index of Mai-Liao sand specimen at low saturation (S = 0%～20%). When saturation is 0%, / of sand specimen is low and when saturation 100% is the high. The ratio is between 0.01～0.035. The Mai-liao sand specimen in lower saturation (S = 0%～20%) will have the situation of rising and then drop. Therefore, the effect of saturation on compression properties of sand is clear.

並列關鍵字

Compression index ； secondary compression index ； unsaturated soil

參考文獻

2. 林育民，民國九十六年，"軟弱黏土壓縮性之實驗研究"，私立中

11. fung, Y. C. (1977) A First Curse in Continuum Mechanics, 2nd ed. Englewood Cliffs, NJ: prent-Hall.

17. Mesri, G., Feng, T. W. , and Benak, J. M. (1990). “Postdensification Penetration Resistance of Clean Sands. ” Journal of Geotechnical Engineering, Vol. 116, No 7.

18. Rendon-Herrero, O. (1983) " Universal Compression Index

19. Rendon-Herrero, O. (1983) " Universal Compression Index