張應變對土壤-地工不織布過濾行為之影響

The Influence of Tensile Strain on Filtration Behavior of Nonwoven Geotextile

侯政賢(Jenq-Shian Hou)

指導教授 ： 洪勇善

淡江大學/工學院/土木工程學系碩士班/碩士(2010年)

https://doi.org/10.6846/TKU.2010.00803

摘要

本研究探討張應變對織物過濾特性之影響，將織物施以不同程度的單向或雙向拉伸後進行坡降比試驗，試驗結果分別以坡降比、土層滲透係數、系統滲流率及土壤流失量等進行分析與比較。本研究選用三種不同厚度(0.8 mm、1.3 mm、2.0 mm)之針軋不織布，以瞭解不同厚度的針軋不織布受影響的程度差異。坡降比試驗係藉由改良自ASTM D5001之坡降比透水儀，依續由小至大變換水力坡降(i = 1、5、10)進行土壤-拉伸之地工織物系統的滲流。同時也以變水頭與濕篩法試驗進行未伸張之不織布的透水速率與開孔徑分佈的量測。
未伸張織物透水速率與開孔徑分佈量測結果顯示，越厚的織物(2.0 mm)有效開孔徑與透水速率皆較小，越薄的織物開孔徑與透水速率皆較大；本研究中，厚度0.8 mm與1.3 mm織物的開孔徑分佈差異不大。
織物受單向張應變時，除張應變2%外，土壤-不織布系統的修正GR值隨張應變增大而有下降趨勢。於中高水力梯度時，修正後的GR值，在張應變7.5%的GR值稍微小於張應變10%的組合，愈薄的不織布則GR值較大。此外，織物與土壤複合層的滲透係數k12，於中高水力梯度時，滲透係數有隨單向張應變的增大而上升的趨勢。
織物承受雙向張應變時，土壤-不織布的修正GR值隨張應變的增大呈現下降的趨勢，系統滲流率也明顯增大。亦即，織物於未伸張時GR值最高，而張應變20%時GR值最低。各種張應變下，於中高水力梯度時，愈薄的不織布GR值較小，愈厚的不織布則GR值較大，此結果與單向張應變情況相反。而織物與土壤複合層的滲透係數k12，於中高水力梯度時，滲透係數有明顯隨張應變增大而上升的趨勢。

關鍵字

地工不織布 ； 針軋 ； 坡降比試驗 ； GR值 ； 張應變 ； 單向 ； 雙向

並列摘要

The influences of tensile stain on filtration characteristics of soil-geotextile combinations were investigated in this study. The geotextiles were stretched and secured to various strain levels, uni-directionally or bi-directionally, prior to installation in a modified GR test apparatus. Test results were expressed in GR values, hydraulic conductivity, and system seepage and soil particle loss. Three needle-punched non-woven geotextiles of different thicknesses (0.8 mm、1.3 mm、2.0 mm) were employed in this study. A falling head and wet sieving methods were carried out collaborated with the strained specimen to evaluate hydraulic conductivity and opening size distribution of the plain geotextiles.
The experimental results show: (1) Thicker geotextile produces smaller apparent opening size and slower flow velocity. (2) For specimens subjected to uniaxial strain, increase of the tensile strain reduces the gradient ratio; the GR values for the system collaborated with stretched geotextiles increase with the decrease of the thickness. (3) For specimens subjected to biaxial strain, increase of the tensile strain reduces the gradient ratio; the GR values for the system collaborated with stretched geotextiles increase with the increase of the thickness. (4) At i = 5 and 10, there is a growth in the hydraulic conductivity for the soil-geotextile layer as the uniaxial or biaxial strains increased.

並列關鍵字

Non-woven geotextiles ； Needle-punched ； Gradient ratio test ； GR value ； Tensile strain ； Uniaxial ； Biaxial

參考文獻

1.王瑞鴻(2006)，“張力作用對織物開孔徑之變化及其過濾特性之探討”，淡江大學土木工程研究所碩士論文，台北。

3.鄭淳軒(2010)，“張應變對針軋不織布開孔徑及滲透速率影響之探討”，淡江大學土木工程研究所碩士論文，台北。

28.Williams N. D., and Luettich S. M., (1990), “Labortory Measurement of Geotextile Filtration Charateristics”, Proceedings of the 4th International Conference on Geotextiles Geomembrances and Related Products, the Hague, Netherlands, pp. 273-278.

4.ASTM D5101, (1992), “Standard Test Method for Measuring the Soil-Geotextile System Clogging Potential by the Gradient Ratio”, Annual Book of ASTM Standard, Section 4,Vol. 04,08, America Society for Testing and Materials, Philadelphia, Pennsylvania, USA, pp. 1190-1196.

9.Christopher, B. R., and Fischer, G. R., (1992), “Geotextile Filtration Principles, Practices and Problems”, Geotextiles and Geomembranes, Vol. 11, Nos. 4-6, pp. 337-353.