重力邊坡變形引致逆向坡撓曲傾覆破壞之可能性探討-以六龜D015大規模崩塌潛勢區之古崩塌為例

The Possibility of flexural toppling Failure Induced by Gravitational Slope Deformation –the Paleo Landslide at Liugui, Kaohsuing,Taiwan as an example

傅政穎(Cheng-Ying Fu)

指導教授 ： 廖志中

國立交通大學/工學院/土木工程系所/碩士(2020年)

摘要

本研究目的為以高雄市六龜區D015大規模崩塌潛勢區為例，探討古崩塌因重力邊坡變形引致撓曲傾覆破壞並進一步產生大規模滑動之可能性。該潛勢區經野外調查及鑽孔內造影等資料顯示，該區域岩層有重力撓曲變形現象。
本研究以適合之理論解析模型(Zheng et al, 2017)，對研究區進行重力撓曲變形力學分析。由一系列參數研究結果得知，影響邊坡撓曲破壞的主要因子為坡趾傾角、岩層不連續面法向方向傾角、岩柱寬度等幾何參數，以及岩石內摩擦角等力學參數；而岩柱間摩擦角、岩石最大張力強度影響較小。
綜合地質調查結果、鑽探岩心資料、孔內造影等及現況地形，發現六龜區D015可能存在兩次以上之大規模崩塌破壞，且在部分中央坑溝邊坡露頭中也可以觀察到撓曲變形現象。本研究首先分析現況地形撓曲傾覆破壞之可能性。再利用現況地形撓曲傾覆破壞下，推估可能的岩柱寬度範圍。再參考鄰近無崩塌區域地形重建古地形面，進行撓曲傾覆破壞分析，推測出本區古崩塌最有可能之破壞模式。最後依照可能性最高之古地形面，提出本研究場址大規模崩塌地質衍育模型，說明六龜D015古崩塌因重力撓曲變形引致大規模崩滑之可能性。

關鍵字

大規模崩塌潛勢區 ； 古崩塌 ； 重力撓曲變形 ； 撓曲傾覆破壞 ； 地質衍育模型

並列摘要

This study aims to investigate the possibility of a paleo landslide caused by gravitational slope flexural toppling deformation. Then, the Paleo Landslide at Liugui, Kaohsuing, Taiwan is selected as a study example.. According to the results of field geological survey and borehole televiewer data. The Liugui paleo landslide may result from a gravitational slope flexural toppling deformation.
This study uses the theoretical analytical model proposed by Zheng et al, (2017) to analyze slope stability of flexural toppling failure. According to the results of a series of parameter study, the main factors that affect the flexural toppling failure of the slope include geometric parameters such as angle of the cut slope with respect to the horizontal direction, angle of the plane normal to the discontinuities with respect to the horizontal direction, thickness of the rock column；and the mechanical parameters such as the friction angle of the intact rock columns, and the friction angle of the discontinuities. But, the tensile strength of the intact rock column have little influence.
Based on the Comprehensive geological survey results, drilling core interpretation, and the borehole televiewer data, it is found that phenomena of flexural deformation and flexural toppling failure could be observed at the outcrops of the gully slopes at the study site, Liugui, Kaohsuing；the site might occur more than two landslides. This study analyzes the possibility of a paleo landslide caused by gravitational slope flexural toppling deformation, and obtains the possible range of thickness of the rock column in accordance with the existing terrain conditions.
Based on the analytical results, it is found that the flexural toppling can cause the slope failure under present terrain and limit thickness of rock column (0.01m-0.3m). Then, this thesis re-constructs the terrain before landslide, referring the topography of the nearby stable slopes. Based on the reconstructed terrain and a series of flexural toppling failure analysis, the failure mechanism of paleo-landslides at the study site is presented. Finally, according to the ancient terrain and the failure mechanism, a geological evolution model is proposed to illustrate the possibility of large-scale paleo-landslide caused by gravity flexural deformation at the Liugui D015.

並列關鍵字

Large-scale landslide potential area ； Paleo landslide ； Gravitational slope Flexural toppling deformation ； Flexural toppling failure ； Geological evolution model

參考文獻

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