||Shaking Table Tests on Geosynthetic Reinforced Slopes -Effects of Slope Angles
||Department of Civil Engineering
||Bongane Dumsane Mhlongo
Shaking Table Tests
Internal Failure Index
A total of six tests were carried out to investigate the effect of slope angles on the seismic behavior of geosynthetic-reinforced soil slopes. It was found that acceleration amplification depends mainly on the input predominant frequency of the earthquake and the variation of slope angles has relatively less significant effect. Acceleration amplification was found to change with elevation which is contrary to the uniform distribution of Am conventionally assumed in current reference design guides (i.e. Elias et al., 2001; NCMA., 2010).
Slope displacements has proven to be largely controlled by the slope angle. Slope displacement increased with increase in slope steepness, irrespective of the input wave frequency used. The magnitude of critical acceleration (ay) detoriates with increase in slope steepness, suggesting that steeper slopes are most likely to fail at relatively small HPGA or ay values. Internal failure index has proven to be an important parameter to distinguish between overturning and bulging modes of failure.
TABLE OF CONTENTS
TABLE OF CONTENT III
LIST OF FIGURES VII
LIST OF TABLES XIII
CHAPTER ONE - INTRODUCTION 1
1.1.Research Background. 1
1.2 Problem Statement. 2
1.3 Objective of Study. 3
1.4 Research Approach. 3
1.5 Scope of Thesis. 4
CHAPTER TWO - LITERATURE REVIEW 6
2.2.Newmark (1965) Sliding Block Model. 8
2.3.Cai and Bathurst (1996) Seismic Induced Permanent Displacement of Geosynthetic-Reinforced Segmental Walls. 10
2.4.Huang et al. (2010) and Huang et al. (2011) Dynamic Behavior of Reinforced Slopes. 12
2.5.Free Vibration, Chopra (2001). 15
2.6.Liao (2018) Wide-Width Test of the Reinforcement Material. 17
2.7.Xu Huoyi (2016) Direct Shear Behavior and Patterning of Soil. 23
2.8.Experimental Design, Instrumentation And Interpretation of Reinforced Soil Wall Response Using Shaking Table (El-Emam and Bathurst, 2004) 24
2.9. Mononobe-Okabe (1926-1929). 27
CHAPTER THREE - EXPERIMENTAL DESIGN AND METHODOLOGY 30
3.2.Soil Properties. 31
3.3.Reinforcement Material. 31
3.4.Model Container. 32
3.6.Instrumentation and Data Acquisition. 33
3.6.1.Accelerometers (Acc). 33
3.6.2.Strain Gauge. 34
3.6.3.Linear Variable Displacement Transducers (LVDTs). 34
3.6.4.National Instrument LabVIEW. 35
3.6.5.Data Acquisition. 35
3.7.MTS Shaking Table. 36
3.8.Testing Methodology. 37
3.9.Input Wave Form Simulation Results. 38
3.10.Scaling Laws. 39
3.11.Sand Specimen Preparation. 40
CHAPTER FOUR - EXPERIEMNTAL RESULTS AND DISCUSSION 57
4.1.Performance of Laminar and Rigid Sand Boxes. 57
4.2.Decay of Free Vibration and White Noise Test. 62
4.3.Acceleration Response. 69
4.4.Wall Deformation Analysis. 91
4.4.1.Maximum Permanent Displacement (Dmax) and Horizontal Peak Ground Acceleration (HPGA). 91
4.4.2.Normalized Slope Displacement (Dn) Vs. Normalized Yield Acceleration (Ay/HPGA). 98
4.5.Deformation Modes. 101
4.5.1.Factor of Safety Analysis. 101
4.5.2.Wall Deformation Process. 109
4.5.3.Internal Failure Index (IFJ). 115
4.6.Distribution of Reinforcement Forces. 118
4.7.Static and Dynamic Earth Pressure Distribution. 126
4.7.1.Active Earth Pressure Coefficient, Ka. 126
4.7.2.Incremental Dynamic Earth Pressure Coefficient, ∆Kdyn. 127
4.7.3.Dynamic Earth Pressure. 132
CHAPTER FIVE - CONCLUSIONS AND SUGGESTIONS 137
5.2.Recommendations for Future Work. 140
Appendix A 146
Appendix B 147
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