以有限元素法分析坡地抗滑樁整治成效-宜專一線12.8K為例

Finite Element Analysis of the Effectiveness of Landslide Control by Piles - Using YizhuanFirst Line 12.8K Landslide Area As an Example

林中村(Chung-Tsun Lin)

指導教授 ： 張寬勇 ； 鄭光炎

國立臺北科技大學/工程學院/環境工程與管理研究所/碩士(2011年)

摘要

台灣山坡地面積約佔全島面積四分之三，林務局所轄管林道均位處此山區內，因地理環境特殊，地形陡峭、坡度大、地質脆弱，常因颱風豪雨造成林道邊坡沖蝕、崩塌、路基流失等災情。宜專一線受921地震與颱風豪雨影響，地質碎裂鬆動，經常造成崩塌災害，其中94年7月18日受海棠颱風侵襲，受創嚴重，以致交通中斷，太平山森林遊樂區關閉近一年。
一般邊坡之災害常於降雨過程或降雨後某段時間內發生，主要原因多來自雨水入滲現象使地下飽和層水位升高，亦增加非飽和層土壤之單位重量，兩者均增加邊坡土體之下滑力。其次由於土壤顆粒含水量逐漸增加，造成土壤剪力強度降低。上述狀況於不同時間下發生並交互影響，使邊坡於降雨發生後於最弱面發生破裂變形，甚至造成滑動、崩塌。
本研究目的主要為分析抗滑樁對地滑潛勢之抑止，以宜專一線12.8K作為實際案例，並透過Stabl與Plaxis程式瞭解地滑整治前、後之常時、暴雨、地震三種狀況下之穩定性，作為未來林務局轄內林道地滑整治之參考依據。分析結果顯示，在滑動深度未知情況下，建議採用PLAXIS軟體分析，與實際現況較為相符；如周邊已有傾斜觀測管監測，滑動深度可明確掌握，則分析可採用STABL程式分析，除程式普遍之優點外，限制滑動深度更能符合現況。本研究案例採抗滑樁工法安全係數約可提升0.15，暴雨情形下，宜專12.8K之B7-B8斷面FS由0.96提升至1.09。
林務局所轄管林道均位處於山區內，山坡地地滑為常見災害之ㄧ，又其中9條林道亦是連接森林遊樂觀光主要之聯絡道路，為保障用路人安全，適度的治理實屬必要。地滑整治策略主要有抑制工法與抑止工法，近年來林務局轄內主要林道（如宜專一線、藤枝林道等）受深層地滑災害時，多採用抗滑樁以抑止地滑潛勢，且施工整治前透過坡地監測以瞭解地滑區之滑動深度、速率與規模，作為工法評估之依據，均得到極佳之成效。

關鍵字

地滑 ； 山坡地監測 ； 邊坡穩定 ； 有限元素法 ； Plaxis ； Stabl

並列摘要

There is about seventy-five percents area of hilly lands in whole Taiwan island, all of the forest roads managed by Forestry Bureau are located in this area, and their slopes were usually eroded, collapsed and destroyed on the part of roads by typhoons and torrential rains, that is owing to their special geographies, including cliffy terrains, steep hillsides and fragile geologies. One of the forest roads, Yilan ROAD “NO.1” , it’s geology is also fragile, and constantly induced landslides collapsing and sliding after Chi-Chi earthquake. Torrential rains and typhoons. In July eighteenth 2005, one of the typhoons called Haitang severely attacked Yilan ROAD “NO.1” , and caused traffic interruption and the Tai-Pin-Shan Forest Recreation Area was forced to close for nearly one year.
Slope damages usually happened in some period within a rainfall or after a rainfall, and mostly because of the water infiltration phenomenon, it rose water level from the groundwater saturated layer, and added the unsaturated layer’s unit soil weight either, both increased the sliding forces of the unit soil, moreover, the soil particles contented much water, the soil lost it’s shearing strength quicker, and this kind of condition occurred in different periods and influenced each other, it induced slopes fractures and deformations at the most weak plane after rainfalls, moreover, it induced collapsing and sliding.
The study chiefly analyzes how effective that the piling to prevent hillside from sliding was, and takes the treatment of 12.8K at Yilan ROAD “NO.1” for example, and applies Stable and Plaxis formulas to measure landslide stability before and after treatment within general time, a torrential rain and an earthquake, three kinds of conditions, and makes a reference of landslide treatment for the forest roads under Forestry Bureau control. The results show that in the case of unknown depth, recommended using PLAXIS formulas to analysis is more in line with the status. In the round of monitoring tubes has been set and grasp the sliding depth, we can use STABL formulas to analysis. In addition to the program’s advantage is popular, if we limited the sliding depth, the result is in keeping with status. The study of piling can enhance the safety factor of 0.15. In status of heavy rain, the piling of Yilan ROAD “NO.1”. 12.8K B7-B8 cross-section safety factor should upgrade from the 0.96 to 1.09.
Hillside sliding is one of the common damages, all of the forest roads managed by Forestry Bureau are located in hillside, nine of them connect forest recreation areas, are the chief traffic roads fir tourism. To protect passersby safety, suitable treatments are necessary. Landslide treatment strategies chiefly combine the method of restraining and the method of prevention, recent year, the main forest roads managed by Forestry Bureau (for instance, Yilan ROAD “NO.1” and Tengihih Forest Road) adopted piling to prevent sliding trend when they took place deep layer sliding, and apply hillside monitoring to measure the sliding depth. Rate and scope before treatments, these kind of method becomes a basis of assessment, and outcome is extremely wall.

並列關鍵字

Landslide ； Hillside Monitoring ； Hillside Stability ； Finite Element Method ； Stabl ； Plaxis

參考文獻

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