臺灣博碩士論文加值系統

近幾年來，加勁擋土牆已廣泛使用成為擋土設施的主流，尤其在各歐、美等國家，加勁擋土牆已為永久建築及交通工程之標準設計。由於加勁擋土牆在耐震上的良好表現，在許多地震頻繁地區加勁擋土牆已成為擋土設施主要設計。1999年9月21日集集大地震發生期間，許多擋土設施發生破壞，其中包含了一向被認為具良好耐震能力的加勁擋土牆。本研究藉此機會收集調查現地土壤和結構於地震發生前後之原始資料及破壞現況，進行數值模擬分析研究，期盼能對工程設計上有所裨益。
本研究之目標在於建立一套疊塊式加勁擋土牆之面牆模擬方法，適用於疊塊式加勁擋土牆之靜動態行為之模擬。依前人所建立有限差分程式（FLAC）模型，以桿件元素（cable element）簡化模擬原用於模擬不同材料元素間之介面元素（interface element）；將混凝土面牆疊塊中回填礫石透水材料之模型，於程式中以桿件元素包覆莫爾庫倫元素模擬之。以Duncan（1980）建立之hyperbolic soil model計算並更新加勁擋土牆背填土壤在不同圍壓下模數變化，以莫爾庫倫元素及桿件元素分別模擬土壤及加勁材。
程式首先選用四座分別位於Algonquin及Royal Military College of Canada之全尺寸試驗牆進行靜態行為之分析模擬，與現場量測牆面變位及加勁材應變、原模型（Lee, 2000）之模擬結果進行比對。所建立之模型於靜態行為分析達合理範圍後，以相同模擬方法輸入地震加速度，選用三座位於台中縣與南投縣內之疊塊式加勁擋土牆進行動態行為分析，將現場觀測破壞情形與程式分析模擬結果比較。最後，進行加勁擋土牆設計參數的分析模擬，考慮設計參數：加勁材料埋設間距及回填土壤夯實度，分析對疊塊式加勁擋土牆之動態行為影響。

Geosynthetic reinforced soil (GRS) retaining walls have been extensively used in recent years. Because of well performance in sustaining seismic loading, GRS retaining structures have become stepwise mainstream of design of retaining wall in many countries occurring earthquake frequently. During the magnitude 7.3 Chi-Chi earthquake that occurred in Taiwan on September 21, 1999, a large number of earth retaining structures failure were observed. These failures offer almost a unique opportunity to investigate the ultimate seismic behavior of various earth retaining structures, including the Geosynthetics reinforced soil (GRS) retaining walls that have generally performed well under seismic loading condition.
Among present GRS retaining systems, modular block faced GRS (MBF-GRS) walls have been recognized as one of the most complicated systems of which seismic performance is very difficult to analyze. In this paper, numerical modeling techniques, which simulate MBF-GRS retaining wall, that are able to perform both static and seismic analyses were developed. In an effort to analyze static and seismic performance of the studied MBF-GRS walls, numerical models were developed using the finite difference method computer program FLAC. FLAC models used in this study were modified from MBF-GRS models developed by Lee (2000). The complicated modular block facing system was simplified as a Mohr-Coulomb material element surrounded with structural cable elements to avoid instability of the many interfaces between different materials.
For static analysis, the geogrid reinforced modular block faced wall of the FHWA Algonquin test wall and three RMCC full scale test walls were reproduced. Instrumentation measurements such as wall deflection and reinforcement strain distributions of the case histories were successfully reproduced. Moreover, results of seismic performance analyses of three MBF-GRS walls in the Da-Kung Village of Taichung Country were also presented. Compared to the filed performance data, the developed numerical models were able to predict the seismic performance of the studied cases in a reasonable range. Finally, issues of seismic design of MBF-GRS walls such as reinforcement spacing and soil compaction are discussed in this paper as well. Discussions and conclusions of this paper are hoped to be of interest to the seismic design and research development of the GRS retaining structures.

Abstract i
Table of Contents iii
List of Figure vi
List of Table xi
Chapter 1 Introduction 1
1-1 Motivation 1
1-2 Research Overview 2
1-3 Thesis Organization 3
Chapter 2 Previous Related Work 4
2-1 Geosynthetic Reinforced Soil Retaining Structures 4
2-1-1 Mechanism of Reinforced Soil Retaining Structures 4
2-1-2 Stability Analyses and Design of GRS Retaining Structure 6
2-1-3 Two Part Wedge Method Design of Reinforced Soil Wall 10
2-2 Techniques for Analysis MBR-GRS retaining wall 11
2-2-1 Limit State stress Analysis 12
2-2-2 Working Stress Analysis 13
2-3 Analytical Models of Reinforced Soil 14
2-3-1 Discrete Element Model 14
2-3-2 Composite Element Model 14
2-3-3 Summary of Numerical Analysis Methods 15
2-4 The Numerical Analysis in Simulating MBF-GRS wall 16
2-5 Object and Scope of This Research 17
2-5-1 Develop numerical techniques that are able to analyze the performance of MBR-GRS retaining Wall 17
2-5-2 Performance of Dynamics Numerical Model 18
2-5-3 Parametric Study of the Seismic Performance Analysis 18
Chapter 3 Developing Numerical Model of Static Analysis of GRS—MBR using Computer Program FLAC 26
3-1 General Description of FLAC 26
3-2 Built-in Material Models 27
3-2-1 Backfill Soil Modeled by Mohr-Coulomb Model 27
3-2-2 Hyperbolic Soil Modulus Model 29
3-2-3 Structural Element built-in FLAC 30
3-3 Construction Modeling 33
3-3-1 Determination of Reinforcement Input Properties 33
3-3-2 Facing System 34
3-3-3 Boundary Condition 35
3-4 Wall Construction 36
3-5 Dynamic Modeling 37
3-5-1 Boundary Condition 37
3-5-2 Input Motion 38
3-5-3 Damping 38
Chapter 4 Static Analysis Performance of Existing MBR-GRS Wall 45
4-1 Introduction 45
4-2 Static Analysis Reproducing Performance of Existing GRS wall 45
4-2-1 Algonquin Modular Block Faced wall 45
4-2-2 Full Scale GRS Test Walls Conducted at the Royal Military College of Canada (RMCC) 46
4-3 Modeling Result 48
4-3-1 Algonquin Modular Block Faced Wall 48
4-3-2 Full-Scale GRS Test Wall Conducted at the Royal Military College of Canada (RMCC) 49
4-4 Discussions and Conclusions 54
Chapter 5 Seismic analysis performance of MBR-GRS retaining wall 84
5-1 Introduction 84
5-2 Seismic Analysis Reproducing Performance of Exiting MBF-GRS Wall 84
5-2-1 Field Description 84
5-2-2 Input Ground Motion 86
5-3 Design Check 86
5-4 Modeling Results 87
5-4-1 Horizontal Wall Displacement 88
5-4-2 Shear Strain Increment Distribution 88
5-4-3 Cable Element Strain Distribution 89
5-4-4 Failure Zone 90
5-5 Discussions and Conclusions 91
Chapter 6 Parametric Study of MBF-GRS wall Under Seismic Condition 111
6-1 Introduction 111
6-2 Preliminary Parametric Study 111
6-3 Analysis Results 112
6-4 Discussions and Conclusion 114
Chapter 7 Conclusions and Recommendations for Future Researches 126
7-1 Conclusion 126
7-2 Recommendations for Future Researches 127
Reference 128

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