改良式砂腸袋護岸工法分析

Abstract

本研究主要探討以改良式砂腸袋為護岸之可行性，基於近年台灣河川土砂淤積量大，本研究以營造生態友善環境為原則，提出以砂腸袋加掛沖刷防護袋為護岸之構想，並探討其可行性；根據本研究過往文獻蒐集分析，過往使用混凝土興建護岸並無法達到生態友善環境，且基礎淘刷是過往護岸工法失敗主因，因此本研究認為可以地工砂腸袋取代原有混凝土護岸，並在砂腸袋下方懸掛沖刷防護袋方式降低因底床淘刷造成的基礎淘空現象；不論是地工砂腸袋或沖刷防護袋，都可採用河床堆積土砂為填充物，此舉將有助於增加通水面積、改善河床棲地環境及減少洪水發生；經本研究至濁水溪旁現場勘查以地工砂腸袋為護岸之工法，確認此想法的確可行；再者經由本研究進行渠槽實驗，比對地工砂腸袋懸掛沖刷防護袋在流況改變與床面沖刷及淤積變化情況上，也發現以地工砂腸袋懸掛沖刷防護袋於砂面下之方式最能降低底床淘刷。本研究也針對改良式砂腸袋護岸與混凝土護岸進行效益分析比較，不論在生態五化分析、碳足跡分析及經濟效益分析上，改良式砂腸袋護岸皆比混凝土護岸有更良好的效益。

The study discusses the practicability of using the revised geotextile tubes as the revetment. Because the sediment yield in Taiwan in the recent decade is massive, the study bases on the establishment of eco-friendly environment, raises the idea of using the geotextile tubes with the anti-erosion bag as the revetment and discusses the practicability. According to the related references, the concrete revetment which is common used in Taiwan can't establish the eco-friendly environment, and the river scour is the main reason for the failure of the concrete revetment. The study considers to use the geotextile tube instead of the original concrete revetment, and hangs the anti-erosion bag at the bottom of the geotextile tube to reduce the river scour. The geotextile tube and anti-erosion bag used in the study can be filled with the deposited sediment in the river, like the gravels. Using the deposited sediment as the loading materials can increase the river flowing area、improve the river habitat environment and reduce the flooding events. Based on the field survey along the Jhuoshuei river, the study confirms that using the geotextile tube as the revetment is practical. The study also proceeds the flume experiments to analyze the distribution of river flowing, scouring and sediment deposition, and the results of the flume experiments shows the best design to avoid the river scour is to hang the anti-erosion bag at the bottom of the geotextile tube.