低滲透非塑性粉土內不織布排水效果與改善措施之試驗研究

Experimental Study on Measures for Improving the Drainage Efficiency of Low-Permeability and Low-Plasticity Silt with Nonwoven Geotextile Drains

林俊佑(Chun-Yu Lin) ； 楊國鑫(Kuo-Hsin Yang)

《中國土木水利工程學刊》 26卷2期 (2014/06) Pp. 181-192

https://doi.org/10.6652/JoCICHE.201406_26(2).0008

摘要

為了改善地工擋土構造物以低滲透性土壤為回填土，在颱風豪雨下之滲流行為與排水能力，本研究設計一座橫向滲流裝置，以粉土為低滲透性土壤、地工不織布為排水材料、搭配不同厚度之薄砂層進行複合排水系統之短期與7日滲流試驗，並於試體上方施加垂直載重模擬覆土壓力。試驗結果發現，無載重時地工不織布對系統滲透性有顯著的提升，但排水效果隨著載重以及滲流時間的增加而減少，原因為不織布受壓後厚度（通水面積）減少以及細顆粒入侵造成排水層阻塞，使其排水效果降低。本研究亦發現設置薄砂層後不論有無載重其排水效果皆能有效發揮，且系統滲透性隨著薄砂層厚度增加而增加。依據本研究成果，建議在實務應用上，可在排水層上下加設一層薄砂層，以有效提升系統的排水效能，降低颱風豪雨造成基礎設施構造物，如道路邊坡與擋土結構物崩塌的災害。

關鍵字

低滲透性土壤 ； 不織布排水層 ； 薄砂層 ； 水力傳導係數 ； 防災

並列摘要

Horizontal permeability tests were conducted experimentally to investigate the short-term and 7-days drainage efficiency (i.e., permeability) of low-permeability soil with permeable nonwoven geotextile drains sandwiched between thin sand layers. The objective of this study was to improve the drainage design of geosynthetic reinforced low-permeability soil structures during heavy rainfall. The test variables included the number of drainage and sand layers, sandlayer thickness, normal pressure, and test duration. The test results indicated that system permeability was effectively improved as the number of drainage and sand layers and sand-layer thickness increased. The system permeability decreased as the applied normal pressure and test duration increased because the normal pressure compressed the thickness of the soil and the drainage layers, and fine soil particles were likely to migrate through seepage over time, resulting in the clogging of drainage layers. The results also demonstrated that the sand layers effectively improved system permeability by preventing fine soil particles from clogging the drainage layers. The system permeability increased as sand-layer thickness increased, suggesting that in addition to functioning as a filter, the sand layers also provided a drainage function. The findings encourage the practical application of thin sand layers to mitigate the damage caused to infrastructure by typhoons or heavy rainfall, thereby achieving a safer and more sustainable environment.

並列關鍵字

low-permeability soil ； nonwoven geotextile drains ； thin sand layer ； hydraulic conductivity ； disaster prevention