不織布護岸承受雙向水流作用下之沖蝕行為研究─以新店溪沖積土壤為例

The Erosion Behavior Of Revetments Using Geotextiles Under Cyclic Flow - A Case Study Of Sindian River

詹秉宏(Bing-Hong Chan)

指導教授 ： 何嘉浚

國立臺北科技大學/工程學院/土木與防災研究所/碩士(2011年)

https://doi.org/10.6841/NTUT.2011.00453

摘要

土壤-地工織物系統之設計，必須具有良好的透水性，以避免孔隙水壓過大而降低護岸之穩定性；另外，地工織物亦需有足夠小的有效開孔徑(apparent opening size, AOS)，以避免土壤流失破壞；以往研究大多以單向水流狀態來探討土壤-地工織物系統之排水與過濾行為，本研究使用自行研發之雙向循環水流試驗儀，進行沖蝕試驗。針對四種不同有效開孔徑之不織布及無凝聚性之新店溪土壤，並且分別採用600, 300, 150及75 sec/cycle等四種不同週期之水流循環，進行一系列之室內試驗。試驗中同步量測孔隙水壓力變化及試體頂部沉陷，以得知土壤-地工織物系統內部應力變化及變形行為，並且於試驗後收集被濾出的土壤，進行粒徑分佈試驗，以探討其沖蝕機制。
試驗結果顯示：(1) 水壓尖峰值隨著水流週期變短而有增加的趨勢，且愈薄的織物所激發的水壓尖峰值愈高；(2) 厚度越厚的地工織物，具有提前催化形成穩定濾層之效果；(3)濾出土壤之顆粒大小受系統內部的孔隙水壓的影響；(4) 地工織物的有效開孔徑、厚度及水流週期，為影響土壤-地工織物過濾系統穩定性之重要因子。

關鍵字

土壤-地工織物系統 ； 不織布 ； 河川護岸 ； 有效開孔徑 ； 雙向循環水流

並列摘要

A suitable geotextile should have good permeability to avoid excessive pore water pressure as well as have small apparent opening size (AOS) to prevent soil particle loss. Most of the researches so far have conducted tests under uni-directional flow condition. Self-development equipment is used for erosion test under cyclic flow. Four geotextiles with different AOS and cohesionless Sindian River alluvium soil were used for this study. A series of tests will be executed under 600, 300, 150 and 75sec/cycle of bi-directional cyclic flow. Moreover, the pore water pressure and settlement on top of sample are measured during testing in order to know the internal stress change of soil. The washout soil particles were collected after test for understanding the amount of washout soil and its particle size distribution.
The results from test displays that: (1) With the shorter cyclic flow, the peak value of pore water pressure will increase gradually. In addition, using the thinner geotextiles would enhance the peak value of pore water pressure. (2)In soil-geotextile system, which includes the geotextiles, the thicker has the ability to catalyze as well as steady in advance the filtration layer. (3) The inner pore water pressure of the soil-geotextile system will influence the particle size of the washout soil. (4) The AOS as well as thickness of geotextiles, cyclic flow are principle factors which can effects the stability of the soil-geotextile system.

並列關鍵字

Soil-geotextiles Filtration System ； Non-woven Geotextile ； River Bank ； Apparent Opening Size (AOS) ； bi-directional cyclic flow

參考文獻

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