錨定織網系統邊坡加勁模型試驗

Model Test for Slope Stabilized by Anchored Geotextile/Geonet System

馮高原(Kao-Yuan Fong)

指導教授 ： 陳榮河

國立臺灣大學/工學院/土木工程學研究所/碩士(2010年)

https://doi.org/10.6342/NTU.2010.01101

摘要

錨定織網系統 (Acnchored geotextile/geonet system, AGS) 係將地工織物或地工網等坡面加勁材以錨釘固定於坡面上，利用坡面加勁材生成圍束力防止表層土壤的破壞，而錨釘亦可防止深層土壤的滑動，國外已有許多成功案例，但國內對此工法的研究與應用尚處於空白階段。
傳統邊坡保護工程多以水泥材料為主，如噴凝土護坡、格樑擋土牆等工法，此類型工法排水性不佳，須在牆背另行製作濾層及排水管導引地下水流出；而水泥表面難以復育植生，對當地的生態景觀造成無法補救的衝擊。此外，受限於混凝土養護條件的限制，若施工程序不佳或養護期間遇雨，會造成材料固結不良，縮短工程壽命，或因地形陡峭，重型機具難以抵達，需花費加倍人力整理施工區域方能進行工程。錨定織網系統則改善了以上缺點，坡面加勁材具良好透水性並能防止土壤流失，坡面植生復育情況良好，對環境衝擊小，且施工期間短不需養護，並可依地形變化改變設計。
本研究主要目的在以模型試驗結果探討錨定織網加勁坡面於不同情況下之保護功用，試驗改變因子有：邊坡坡角、錨定力大小、錨定型式、滲流條件等。試驗過程影像利用質點影像測速儀 (PIV) 分析顆粒運動的趨勢，並將試驗求得之極限錨定力，以極限平衡法分析破壞面的安全係數，以了解此加勁系統的力學機制。以鋼線施加錨定力於坡面，乾坡試驗破壞較類似楔型，溼坡試驗則全為弧形滑動；以土釘錨定坡面，會發生加勁區土壤大規模滑移之現象。試驗過程中，坡面加勁材發揮良好阻留功效，在破壞發生前後皆能防止邊坡土壤流失。而若單階錨定失效，其他階錨定仍能發揮功效，阻止更進一步的破壞發生。

關鍵字

邊坡 ； 加勁邊坡 ； 錨定織網 ； 模型試驗 ； PIV

並列摘要

Anchored geotextile/geonet system (AGS) is a method for protecting slopes. A geotextile or geonet is covered over the surface of a slope, driven by ground anchors through its reinforced openings into the underlying soil mass, and fixed on the slope. The fabric can provide confining strength to prevent failure on the slope surface, and the anchors can maintain stability of the slope. There are many successful application cases abroad. However, there are no research nor application for in-situ slope of this slope protection method in Taiwan. From economical and ecological view points, the use of AGS as a protection method for slopes not only decreases the expenses and duration of construction, but also improves the environment.
Model tests are used to understand the reinforced slope failure behavior and the mechanism of failure of this system. This research is to establish a series of model tests on slopes formed by sandy soil. The change of slope angle, anchorage force, anchor type, and seepage condition were probed in this study. The particle image velocimetry (PIV) measurement technique was used to investigate the soil movement during failure process, and limit equilibrium method was used to derive the factor of safety of failure plane.
The results of steel wire anchored slope tests show that dry slope tests have a failure shape similar to a wedge, and wet slope tests have a circular failure surface. The results of soil nail anchored slope tests show that the failure zone is equal to the reinforced soil which moves horizontally forward. The geotextile can prevent soil loss during the whole test. Even if single row of anchorage force is lost, the other row of anchorage force can still help prevent further failure.

並列關鍵字

slope ； reinforced slope ； anchored geotextile/geonet system ； model test ； PIV

參考文獻

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14. ASTM D4253-00, “Standard Test Methods for Maximum Index Density and Unit Weight of Soils Using Vibratory Table ,” ASTM International, West Conshohocken, PA, USA.