板岩逆向坡之穩定性控制因子研究

A Study on Evaluating the Stability Factors of Anti-dip Slate Slopes

李沅昶(Yuan-Chang Li)

指導教授 ： 鄭富書

共同指導教授 ： 翁孟嘉(Meng-Chia Weng)

國立臺灣大學/工學院/土木工程學研究所/碩士(2018年)

https://doi.org/10.6342/NTU201803818

摘要

板岩邊坡中傾倒破壞為其中一種主要破壞型態，受到坡高、坡角、弱面傾角與材料強度等因素影響。為了探討板岩葉理強度與決定破壞準則，本研究進行一系列之張力試驗與直接剪力試驗。此外，本研究將所提出之破壞準則運用於分離元素法UDEC中，以模擬板岩邊坡之傾倒破壞於不同條件下，如材料狀態(乾式、濕式)、不同弱面傾角、坡角與坡高。本研究結果總結如下：(1) 板岩葉理面破壞曲線實驗結果顯示，在低正向應力時，其呈現高度非線性，此時之摩擦角有明顯高於高正向應力時之摩擦角；(2) 比較乾燥與濕式實驗結果發現，試體呈現遇水弱化情況；(3) 破壞面傾斜與跳階皆會提升剪力強度；(4) 板岩微觀下為片狀，破裂面為片狀堆積之鋸齒狀；(5) 採用非線性回歸模擬結果較線性回歸更能表現出張裂情況與傾倒行為；(6) 坡角與傾角關係會影響破壞結果與型態；(7) 隨著坡高增加，傾倒破壞越明顯且受到坡角與傾角影響。

關鍵字

逆向坡 ； 傾倒破壞 ； 分離元素法 ； 板岩 ； 直接剪力試驗 ； 葉理張力試驗

並列摘要

Toppling failure is one major failure types of slate slope, which is affected by many factors, such as slope height, slope angle, dip angle and material strength, etc. To investigate the strength and detremine the failure criteria of slate foliation, this study conducted a series of pull-off test and direct shear tests. Furthermore, this study implement the proposed failure criteria in distinct element software UDEC to simulate toppling failure of slate slopes under different conditions such as dry, and wet condition ,different dip angles and different slope angles and different slope heights. The results of this study are summerized as follows: (1) The experimental results show that the failure criteria of foliation is highly nonlinear in low normal stress. (2) Compared with the results from dry and wet condition, the slate exhibits wet-weakening effect. (3) When the failure pattern exhibits stepped failure, the shear strength is greater than that of planar failure. (4) In microscopic view, slate is sheet arrangement and it is jagged at the crack. (5) The simulation based on the proposed failure criteria exhibits more reasonable results. (6) The relationship of slope angle and dip angle will influence the failure type and result. (7) Increasing the slope height, toppling failure is more significant.

並列關鍵字

anti-dip slope ； toppling failure ； distinct element method ； slates ； direct shear test ； foliation tensile strength test

參考文獻

參考文獻

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[2] Adhikary, D. P., & Dyskin, A. V. (2007). Modelling of progressive and instantaneous failures of foliated rock slopes. Rock Mechanics and Rock Engineering, 40(4), 349-362.

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[4] ASTM, D. 5731-95. Standard test method for determination of the point load strength index of rock, American Society for Testing and Materials.