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Soil Compaction Models In a first step (Section 6.3.1) this “in-situ virgin compression line (in-situ VCL)” will be derived from theoretical considerations. Afterwards (Section 6.3.2) the in-situ VCL is created utilizing treatments from the soil bin. The in-situ VCL will be validated with inde- pendent soil bin laboratory data (Section 6.3.3) and the entire concept validated in field conditions (Section 6.3.4). In the subsequent section (Section 6.4) the in-situ approach will be applied to tracks. Then the in-situ VCL approach is repeated with small scale plate sinkage experiments (Section 6.5). After gaining the slope and intercept of the in-situ VCL, these parameters will be verified in a triaxial cell test apparatus (Section 6.6). 6.3.1 Theoretical Considerations The Cam-Clay model COMPSOIL (O’Sullivan et al., 1998) provides an estimation of soil displacement for a sandy loam soil from tyre data and DBD whereby COMPSOIL calcu- lates VCL parameters depending on moisture content. An initial comparison of soil displacement measured by Ansorge (2005, a) for a sandy loam to the data predicted by COMPSOIL using the VCL parameters suggested by O’Sullivan et al. (1998) is given in Figure 69 originating from Ansorge (2005, a). This shows very large deviations for both uniform and stratified soils, which in turn suggests that either the soil specific parameters used to describe the sandy loam soil of the model are not adequate to describe the sandy loam soil used in the soil bin or there are substantial errors in the model. The latter is unlikely as O’Sullivan et al. (1998) demonstrated close agreement. Consequently the VCL parameters for the sandy loam of the Cotternham Series (which was used by Ansorge (2005, a) and this study) have to be different from the sandy loam soil described by O’Sullivan et al. (1998) and used by the original COMPSOIL model and hence need to be determined. A VCL is usually obtained from plotting the relative density (ratio of the maximum soil density (2.66 g/cm 3 ) to the resulting dry bulk density) against mean normal pressure measured with triaxial cell tests. For the assessment of the in-situ VCL in the soil bin the relative density is obtained by adding the average density increase measured by Ansorge (2005, a) and this study to the initial soil density. Mean normal pressure is obtained from the contact pressure following a transformation after O’Sullivan et al. (1998). Ph.D. Thesis Dirk Ansorge (2007) 104
Soil Compaction Models Depth (mm) -20 0 20 40 60 80 100 0 100 200 300 400 500 600 700 800 Displacement (mm) Figure 69: Measured (solid line) and predicted (broken line) soil displacement for 900mm section width tyre at 10.5t load and 1.9bar inflation pressure on uniform (□) and stratified (×) soil conditions (measured data from Ansorge, 2005, a) This approach does not take into account the elastic recovery of the soil, and consequently will potentially yield a VCL indicating the soil to be slightly too strong. A calculation, detailed in Appendix 11.1.2.1, yields a 0.87 % error from neglecting elastic recovery for the relative density measurement indicating a marginally stronger soil. This small error is accepted as it will affect all treatments similarly. 6.3.2 Practical Derivation of VCL Parameters As shown in 6.2.1 the semi-empirically estimated contact pressure from O’Sullivan et al. (1998), is in good agreement with the contact pressure determined by Ansorge (2005, a) and this study. The confining pressures � 2 and � 3 can be derived from the following equation gained by O’Sullivan et al. (1998) from empirical regression lines: � 1 ln c1 � z � c2 � A � c � n � 3 �� Eq. 6 Ph.D. Thesis Dirk Ansorge (2007) 105
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Cranfield University School of Appl
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Abstract Ancillary experiments show
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Table of Contents TABLE OF CONTENTS
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Table of Contents 4.1.3 Analysis of
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Table of Contents 11.1.1.1 Comparis
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List of Figures and Tables Figure 3
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List of Figures and Tables Figure 1
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Nomenclature NOMENCLATURE Abbreviat
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Introduction 1 INTRODUCTION 1.1 Bac
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Introduction � Ansorge, D. and Go
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Introduction 1.2 Aim To elucidate t
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Introduction a) the soil compaction
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Experimental Methods 2.1.1.1 Test F
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Experimental Methods had been mount
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Experimental Methods track; the loa
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Experimental Methods 800/10.5/2.5 t
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Experimental Methods term. In the m
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Experimental Methods Soil Surface F
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Experimental Methods Depth (cm) 0 1
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Experimental Methods ence surface c
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Experimental Methods chine derives
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Experimental Methods depth. The dat
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Experimental Methods with water and
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Experimental Methods 2.4 Statistica
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Laboratory Studies Into Undercarria
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Page 69 and 70: Laboratory Studies Into Undercarria
Page 77 and 78: Field Study With Full Size Combine
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Page 107 and 108: Soil Compaction Models sibilities t
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Page 111 and 112: Soil Compaction Models Wroth (1968)
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Page 117 and 118: Soil Compaction Models Utilizing Ke
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Page 123 and 124: Soil Compaction Models ture content
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Page 127 and 128: Soil Compaction Models Predicted In
Page 129 and 130: Soil Compaction Models Depth (mm) -
Page 131 and 132: Soil Compaction Models and 13.7 % b
Page 133 and 134: Soil Compaction Models Rel. Density
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Page 137 and 138: Soil Compaction Models The approach
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Page 141 and 142: Soil Compaction Models This result
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Page 145 and 146: Soil Compaction Models σσ 1 (kPA)
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Page 149 and 150: Soil Compaction Models The response
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Page 153 and 154: Soil Compaction Models SOILFLEX tak
Page 155 and 156: Ancillary Experiments 7 ANCILLARY E
Page 157 and 158: Ancillary Experiments Average conta
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Page 169 and 170: Ancillary Experiments 7.3.2 Influen
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Ancillary Experiments The results f
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Ancillary Experiments Figure 117: S
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Ancillary Experiments Contact Press
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Ancillary Experiments Figure 123: F
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Ancillary Experiments Sinkage (mm)
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Ancillary Experiments model which o
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Ancillary Experiments 7.3.5 The Inf
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Ancillary Experiments 7.3.7 Discuss
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Ancillary Experiments Terzaghi (194
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Ancillary Experiments contact area.
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Ancillary Experiments soil forward
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Conclusions � The longitudinal so
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Bibliography 10 BIBLIOGRAPHY Aboaba
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Bibliography Defossez, P., Richard,
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Bibliography Gregory, A.S.; Whalley
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Bibliography Lamande, M., Schjonnin
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Bibliography Seig, D., 1985. Soil C
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Appendix 11 APPENDIX Ph.D. Thesis D
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Appendix Figure 32: VCL sample at t
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Appendix comparison at the deepest
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Appendix Estimated Pressure (kPa) 2
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Appendix 11.1.1.2.1 SOCOMO One of t
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Appendix by Seig (1985) who showed
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Appendix Soil water content 15 % an
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Appendix Adapting critical state so
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Appendix density is obtained by add
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Appendix Table 5: Values of constan
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Appendix choice of a concentration
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Appendix 11.1.3.1 Dense/Hard and Lo
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Appendix 11.1.3.2 Stratified Soil C
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Appendix To summarize the ability t
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Appendix In the following the predi
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Appendix concentration factor of 4,
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Appendix 11.1.5.1 Confining Pressur
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Appendix Figure 24. The VCL created
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Appendix Rel. Density 2 1,9 1,8 1,7
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Appendix relation of � 1 to � 2
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Appendix Rel. Density 2 1,9 1,8 1,7
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Appendix Rel. Density 1,7 1,68 1,66
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Appendix Depth (mm) 0,0 100,0 200,0
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Appendix Figure 42: Plate in cookin
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Appendix � z � � �� k c p
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Appendix Table 8: n and k depending
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Appendix to the plate sinkage equat
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Appendix with a slight deviation fr
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Appendix Table 12: DBD values for a
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