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研究生： 張維洋
Wei-Yang Chang
論文名稱： 三軸試驗下加勁材勁度對加勁土壤力學行為之影響
Influence of Reinforcement Stiffness on the Behavior of Reinforced Soil under Triaxial Compression Tests
指導教授： 楊國鑫
Kuo-Hsin Yang
口試委員: 林宏達
Horn-Da Lin
洪勇善
Yong-Shan Hong
學位類別： 碩士
Master
系所名稱： 工程學院 - 營建工程系
Department of Civil and Construction Engineering
論文出版年： 2013
畢業學年度： 101
語文別： 英文
論文頁數： 110
中文關鍵詞： 地工合成材 、不織布 、加勁材勁度 、加勁土壤 、三軸壓縮試驗 、加勁材張力 、加勁材應變
外文關鍵詞： Reinforcement Stiffness, Reinforced Soil, Triaxial Compression Test, Reinforcement Tensile Strain and Force
相關次數： 點閱：282  下載：4 
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    • 目前加勁擋土結構物的設計中，加勁材材料的最大張力強度為加勁材主要且唯一的設計參數，然而加勁材勁度的影響並沒有被充分的考慮到。事實上，當土壤產生主動破壞時，加勁材尚未達到其最大張力強度，其力學行為應該為加勁材勁度或是某應變量下相對應的張力強度所控制。以上可見，目前的設計概念與加勁擋土結構物在工作應力下之實際行為並不相符合。有鑑於此，本研究選用兩種勁度不同之不織布作為加勁材，採用三軸壓縮試驗模擬加勁土壤於加勁擋土結構物內之受力行為，探討加勁材勁度對加勁土壤之影響。本研究試驗結果發現，在高圍壓與小加勁間距下，加勁材勁度的增加可提升加勁土壤之剪力強度，束制加勁土壤之體積應變，且其加勁效果能越早發揮。然而，在低圍壓與大加勁間隔下，由於土壤與勁度大之加勁材的互制效果較勁度小之加勁材來的差，故試驗觀察到加勁材勁度的增加反而會降低加勁土壤之剪力強度。本研究更進一步對加勁材張力與應變發展進行探討，試驗結果發現，加勁材最大張應變與加勁層數、圍壓呈現正關係而與加勁材勁度呈現負關係。研究結果也發現加勁土壤的強度差異Δσ1 與加勁材最大累加張力ΣTmax呈現非唯一之關係。本研究在最後也利用三種預測公式對加勁土壤之尖峰剪力強度進行預測並與三軸壓縮試驗所量測之實際值進行比較。本研究成果有助於了解加勁材勁度對加勁土壤之影響，並進一步提供往後發展利用加勁材勁度為加勁擋土結構物之設計方法的理論依據。

    In the current design guidelines of geosynthetic-reinforced soil (GRS) structures, the ultimate tensile strength of reinforcement is the only reinforcement parameter for internal stability design against breakage. The effect of reinforcement stiffness has not been considered into the design yet. The objective of this research is to study the influence of reinforcement stiffness on the stress-strain-volumetric behavior of reinforced soil. A series of triaxial compression tests on reinforced soil were carried out using two types of reinforcement with different stiffness. The experimental results showed that, under high confining pressure and close reinforcement spacing, the geotextile reinforcement with larger stiffness enhanced the reinforced soil shear strength, suppressed the volumetric strain and required less deformation for the reinforced soil shear strength to exceed the unreinforced one (strength ratio ≥1.0). However, under low confining pressure and large reinforcement spacing; the shear strength of soil reinforced with stiff reinforcement was found to be lower than that reinforced with flexible one. Furthermore, a special technique was introduced in the study to deduce the mobilization of reinforcement tensile strains after tests from the measured residual reinforcement tensile strains. The experimental results show that the tensile strain and force of reinforcement depends on reinforcement spacing and stiffness and confining pressure. Experimental results show that the maximum mobilized tensile strain has positive correlation with the confining pressure and number of reinforcement layer and negative correlation with the reinforcement stiffness. Depending on the reinforcement stiffness, this study found there is not unique relationship between the sum of maximum tensile force ΣTmax and the strength difference between reinforced and unreinforced soil Δσ1, which violate the conventional limit equilibrium solution for the prediction of peak shear strength of reinforced soil. Last, the peak shear strength of reinforced soil with two reinforcement types was compared with the results predicted by three analytical methods. The accuracy of these three methods was discussed at the end.

    ABSTRACT I TABLE OF CONTENTS III LIST OF TABLES VI LIST OF FIGURES VI CHAPTER 1 INTRODUCTION 1 1.1 Background 1 1.2 Objectives 2 1.3 Thesis Structure 2 CHAPTER 2 LITERATURE REVIEW 5 2.1 Design of Geosynthetic-Reinforced Soil (GRS) Retaining Structures 5 2.1.1 Lateral earth pressure method 5 2.1.2 Limit equilibriummethod 8 2.1.3 Continuum mechanics method 8 2.1.4 K-stiffness method 9 2.2 Mechanical Behavior of Reinforced Specimen in Triaxial Compression Test 10 2.2.1 Schlosser and Vidal (1980) 10 2.2.2 Haeri et al (2000) 10 2.2.3 Latha and Murthy (2006) 13 2.2.4 Tsai (2007) 13 2.3 Numerical Analysis of Reinforced Soil 14 2.3.1 Wu and Hong (2008) 14 2.3.2 Yang (2010) 14 2.4 Development of tensile strain and force for the deformed reinforcement 16 2.4.1 Leshchinsky (2010) 16 2.4.2 Chandrasekaran et al. (1989) 16 2.5 Prediction methods for the reinforced specimen 17 2.5.1 Additional internal confinement method 17 2.5.2 Apparent cohesion and modified apparent cohesion method 17 CHAPTER 3 PHYSICAL PROPERTIES OF TEST MATERALS 19 3.1 Test Program 19 3.2 Test Soils 19 3.2.1 Soil physical properties 19 3.2.2 Relative density test 20 3.2.3 Direct shear test 22 3.3 Geotextile 25 3.3.1 Wide-width tensile test 25 3.3.2 Biaxial tensile test 27 3.3.3 Axisymmetric tensile test 28 3.4 Summary All of Tensile Test Results 35 3.5 Soil-Geosynthetic Interface Direct Shear Test 41 CHAPTER 4 TEST METHOD AND PROGRAM 43 4.1 Triaxial Compression Test System 43 4.1.2 Calibration of test instrument 47 4.1.3 Automatic data acquisition system 52 4.1.4 Specimen preparation and test procedure 54 4.2 Test Program 58 CHAPTER 5 STRESS-STRAIN-VOLUME BEHAVIOR 60 5.1 Results 60 5.1.1 Unreinforced soil 60 5.1.2 Single layer reinforced soil 62 5.1.3 Two layers reinforced soil 64 5.1.4 Three layers reinforced soil 65 5.2 Comparisons and Discussions 67 5.3 Failure Pattern 72 5.4 The Effect of Strength Improvement 73 5.4.1 Strength ratio 73 5.4.2 Strength difference 75 5.5 Failure Envelopes 77 CHAPTER 6 REINFORCEMENT TENSILE STRAIN AND TENSILE FORCE WITH SPECIMENS 78 6.1 Technique for Measurement of Reinforcement Residual Tensile Strain 78 6.2 Relationships between Mobilized Tensile Strain and Residual Tensile Strain 83 6.3 Mobilized Tensile Strain 85 6.4 Maximum Residual Tensile Strain 91 6.5 Maximum Mobilized Tensile Strain 92 6.6 Maximum Mobilized Tensile Force 93 6.7 Comparison of Analytical Models 98 6.7.1 Apparent cohesion approach 98 6.7.2 Modified apparent cohesion approach 98 6.7.3 Additional internal confinement approach 99 6.8 Comparison between Experimental and Predicted Peak Axial Stress 100 CHAPTER 7 CONCLUSIONS AND RECOMMENDATION 103 7.1 Conclusions 103 7.2 Recommendations 106 REFERENCES 107

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