彈塑性褶皺曲滑模式之數值研究

Flexural slip behaviors of buckling folds in elasto-plastic layer revealed by numerical analysis

湯翰昕(Han-Shin Tang)

指導教授 ： 鄭富書

共同指導教授 ： 黃國品

國立臺灣大學/工學院/土木工程學研究所/碩士(2009年)

https://doi.org/10.6342/NTU.2009.03126

摘要

褶皺係指地殼變動過程中，板塊相互碰撞造成地層呈現彎曲形態之地質構造。前人研究已提出不同地層材料組合中單層褶皺之理論解，並以數值模擬方法加以驗證與比對，惟其中地層交界假設為無界面情況，且材料並未考慮塑性行為之影響，對於真實地層材料與其界面行為之了解恐尚有遺漏，如使褶皺軸部出現孔洞之曲滑作用（flexural slip）與尖頂褶皺（chevron fold）之塑性鉸，以及岩層發生塑性時機與單層褶皺理論解間之關係，故本研究立於前人建構之基礎，進而探討層間界面性質與覆岩圍壓對彈塑性褶皺行為之影響。
本研究採用數值模擬分析方式針對欲了解之影響因子進行探討，以理論解與分析結果相互比對作為影響趨勢之判定。研究中藉數值軟體ABAQUS為模擬工具，以均佈力方式賦予地層深度之覆岩圍壓；以摩擦性質簡化地層界面膠結之複雜行為；以位移控制邊界仿效地層受擠壓之過程，並先以彈性材料進行分析，由單純材料特性下之褶皺行為，釐清塑性材料對褶皺調適方式與形貌之差異影響。
彈性褶皺之模擬結果中，岩層發生挫屈時產生之褶皺波長均與理論解相近，表示摩擦界面與覆岩圍壓對岩層挫屈行為影響並不顯著，但於其後繼續擠壓形成單頻與雙頻波形褶皺之過程，褶皺軸部會因曲滑行為之調整而產生孔洞，而其層間摩擦界面性質束制岩層與介質發生相對滑移，並改變褶皺調整變形之行為；覆岩圍壓則會抑制雙頻波形褶皺中高頻波形之特徵，以及孔洞出現之程度。
彈塑性褶皺之模擬結果中，層間摩擦界面對岩層挫屈行為亦無太大影響；但覆岩圍壓對於彈塑性材料發生塑性之時機將決定岩層挫屈後之行為，當岩層先產生塑性而後挫屈，可能將無法形成褶皺，意即岩層挫屈時會於某弱面處產生斷裂；而當岩層挫屈後產生塑性，所形成之褶皺將因塑性產生位置及程度造成變形與調整行為之差異。故由研究結果可推斷，隨岩層發生塑性時機之延後，將依序觀察到斷層、覆瓦狀構造、單頻波形褶皺及雙頻波形褶皺之形成。

關鍵字

數值模擬 ； 曲滑作用 ； 孔洞 ； 尖頂褶皺 ； 塑性鉸 ； 界面性質 ； 覆岩圍壓

並列摘要

During diastrophism, the plates collide with each other has caused a bending of the geological structure which is called fold. In Previous studies have been made of different material combinations formation of single-layer fold of the theoretical solution and numerical simulation methods to validate the comparison, but which at the junction formation is assumed to be the case without the interface and the material does not take the effect of yield behavior, for real geotectonic material to understand its interface behavior may still missing, such as flexural slip result in fold axis having cavities and chevron fold of plastic hinge, as well as the relationship between the timing of rock layer yield and the theoretical solution of single-layer fold, so this study was to build the basis of an earlier, and then explore the influence of the interfacial properties between layers of overlying strata and confining pressure on elasto-plastic folds.
In this study, using numerical analysis to discuss the impact factor and then taking the results of the analysis compare with the theoretical solution for determine the impact of the trend. To select ABAQUS software as simulation tool, and using the uniform force to give the confining pressure of the depth of rock strata; using friction property to simplify the complexity of the interface bonding behavior of strata; using displacement control the border to simulate the process of strata by extrusion.
The simulation results of elastic folds, the wavelength of buckling fold is similar to the theoretical solution, it means that friction interface and the confining pressure of overlying strata is not significantly affected, but during process of its extrusion to form single-frequency dual- frequency waveform, fold axis will be arose cavities by flexural-slip folding, and the interfacial properties between layers will restrict the relative slip occurred between rock layer and matrix and change the adjustment deformation behavior of fold; confining pressure of overlying strata will inhibit the characteristics of high-frequency waveforms of dual-frequency waveform fold, as well as the degree of emergence cavities.
The simulation results of elasto-plastic folds, the friction interface between layers there is little impact on buckling behavior of rock layer; but confining pressure of overlying strata for the timing of the elasto-plastic materials yield will determine the post-buckle behavior of rock layer, when the rock layer first yield and then buckling will not be able to form a fold, which means rock layer will fracture from a weak surface during the moment of buckling; and when the rock layer yield after buckling, the formation of the fold will have different adjustment and deformation caused by the place and degree of yield. It can be inferred from the study, with the time delay of rock layer yield will be observed that the fault then, duplex, single-frequency waveform folds and dual-frequency waveform folds.

並列關鍵字

numerical simulation ； flexural slip ； cavity ； chevron fold ； plastic hinge ； interfacial properties ； confining pressure

參考文獻

黃國品（2006）：單層岩層褶皺力學機制探討，國立台灣大學土木工程研究所博士論文，台北。

蔡立盛（2005）：砂岩依時性力學特性研究及應用，國立台灣大學土木工程研究所博士論文，台北。

鄭添耀（2007）：褶皺的曲滑作用模式數值模擬初探，國立台灣大學土木工程研究所碩士論文，台北。

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