面層加勁系統之邊坡模型試驗

Model Tests of Slopes with a Reinforced Facing System

林育崇(Yu-Chung Lin)

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(2008年)

https://doi.org/10.6342/NTU.2008.00358

摘要

加勁面層工法使用砂土混合膠合劑、植物種子以及地工纖維材料，噴灑於邊坡表面形成面層；亦可配合於坡面打設土釘，增加內部穩定功效。傳統的護坡工法大多使用混凝土施築擋土構造，然混凝土表面光滑且無法配合植生，對現地景觀及環境產生極大的影響，且因材料較為剛性，容易受氣候變化或局部變形的影響而開裂。加勁面層工法則改善了傳統護坡工法的缺點，藉由添加地工纖維來增加面層材料之延展性，提高其抵抗變形的能力，並且可於面層材料中加入植物種子以進行植生綠化，降低工程對環境的衝擊。 然而，由於面層加勁工法相關之研究資料有限，故有部份力學性質尚待釐清，因此有必要進行更多的研究探討。本研究之主要目的便在探討加勁面層工法於邊坡頂部受荷重時之牆體變形性、背填土沉陷量及擋土結構的破壞形式等，以期能對破壞機制有更進一步的瞭解。本研究主要係利用一自行研發之模型砂箱，對純砂邊坡進行一系列的相關試驗，並且透過模型相似性分析，於試驗室內製作出模擬現地實際尺寸之纖維加勁面層護坡結構模型，並透過邊坡坡頂加載之方式，使面層擋土結構產生破壞，同時記錄面層於各加載階段所產生的變位。 研究項目主要改變加勁面層厚度、邊坡坡角、纖維含量及面層之結構型式等，以探討各因子對加勁面層穩定性的影響。試驗結果發現當面層厚度增加時，可有效減少其水帄位移量及坡頂沉陷量；在相同荷重作用下，面層水帄位移量及沉陷量隨著坡角的變陡而增加；而且，纖維可有效提高面層之穩定性，降低牆面變形；另外，採用上窄下寬之重力式擋土牆型式與採用均勻厚度之面層具有相當的穩定效果，但卻較為經濟。

關鍵字

邊坡 ； 加勁面層 ； 模型試驗 ； 纖維 ； 位移

並列摘要

Fiber-reinforced facing system is a method for protecting slopes. It is made of a mixture of sands, adhesives, seeds and fiber, which is ejected onto the slope face to form a reinforced-facing. It may also uses soil-nails to increase the stability of slopes. From aesthetic and ecological points of view, the use of fiber-reinforced facing as a protection material for slopes not only increase the ductility of material to improve its ability of resisting deformation, but also improve the ecology of the environment. In order to understand the mechanism of failure of this system, this study investigates the structure deformation, backfill settlement, and failure mode of the reinforced-facing system using laboratory experiments. A sand box was adapted to carry out a series of model tests on slopes formed by sandy soil. The model similarity was considered to set up the models of reinforced-facing system for simulating the actual condition on site. Surcharge was applied on the top of the slope and the deformation of slopes was recorded till the system was failed. The thickness of facing, slope angle, fiber content, and the facing type of were probed in this study. The results of model tests show that the horizontal displacement of the facing and the backfill settlement decreased with the increase of facing thickness, however, they increased with the the slope angle. In addition, the facing which contains fibers decreased the deformation. Moreover, the gravity-type facing, 2cm thick at top and 4cm thick at bottom, had similar effect in resisting deformation of slope as the 4-cm thick facing. However, the gravitiy type needs less material than the equal-width facing type.

並列關鍵字

slope ； reinforced-facing system ； model test ； fibers ； displacement

參考文獻

1. 邱佑銘（2005），「蜂巢格網擋土結構模型試驗」，碩士論文，國立台灣大學土木工程學系，133頁。

2. 吳泰慶 (2008)，「連續纖維加勁砂土抗剪行為」，碩士論文，國立台灣大學土木工程學系，99頁。

6. 陳怡儂（2007），「利用模型試驗探討顆粒性土壤邊坡滑動之行為」，碩士論文，國立台灣大學土木工程學系，102頁。

7. 陳榮河，何嘉浚(2003)，「土釘擋土工法導論」，地工技術，第98期，第5-16頁。

8. ASTM D 422. Standard Test Method for Particle-Size Analysis of Soils. ASTM International, West Conshohocken, PA, USA.