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Soil Compaction Models The “in-situ VCL full pressure” gained by assuming contact pressure being equal to mean normal stress agrees well with a typical VCL from the triaxial tests whereby only confining pressure has been applied (“VCL Spherical Pressure”). However, this underestimates soil displacement by a factor of 2. If constant confining stress is applied and an axial load impact similar to that in the soil bin is applied, and if the height change is additionally to the cell volume change taken into account (“VCL A+R Height / Quick”) soil displacement is largely overestimated. With only cell volume change (“VCL A+R Quick”) the approach is closer to the prediction with the tyres, however, slightly underestimates the resulting sinkage. If the axial load is applied slowly by a constant strain rate and only cell volume change is taken into consideration (“VCL A+R Slow”) the correct shape is obtained and it underestimates total displacement less than “VCL A+R Quick”. If in the slow case height change is taken into consideration, too, “VCL A+R Height / Slow” shows a closer agreement at the surface, but the entire shape of the curve changed making it less appropriate. Thus the VCL which shows the closest agreement to the in-situ VCL in the previous Section pro- vides the parameters for the closest prediction. Depth (mm) 0 100 200 300 400 500 600 700 800 Displacement (mm) 0 50 100 150 200 250 300 350 400 Measured 900/10.5/1.9 in-situ VCL in-situ VCL full Pressure VCL SphericalPressure VCL A+RHeight / Slow VCL A+RHeight / Quick VCL A+R Slow VCL A+RQuick Figure 93: Comparison of prediction of 900/10.5/1.9 tyre with different triaxially gained VCLs to describe The following Figure 94 compares in detail the average VCL gained from axial and radial loading but only considering cell volume change and the VCL gained from mere confining Ph.D. Thesis Dirk Ansorge (2007) 130
Soil Compaction Models pressure to the initial soil data and in-situ prediction. Soil displacement for the two triaxially gained VCL predictions is overestimated at depth and underestimated at the surface. Rut depth and shape of the soil displacement curve was predicted closest utilizing the in- situ VCL which again pronounces the quality and success of this method. It appears that the triaxially gained VCLs describe the soil displacement behavior more linearly than it actually is and than it is predicted with the in-situ VCL. Depth (mm) 0,0 100,0 200,0 300,0 400,0 500,0 600,0 700,0 800,0 Displacement (mm) 0 20 40 60 80 100 120 Confining VCL Measured 900/10.5/1.9 Averaged Radial and Axial VCL in-situ VCL Figure 94: Predicted soil displacement using averaged VCLs at 1.4 g/cm 3 Very interesting is that VCLs which should uniquely describe soil density change with pressure depending on mean normal pressure differ significantly if � 1 is larger than � 2 and� 3 , i.e. if additional axial load is applied. The VCL depends on the stress state of � 1, � 2 ,and� 3 and only if these represent real field conditions the VCL does correspond with the VCL gained from the passage of the tyres. Ph.D. Thesis Dirk Ansorge (2007) LSD 6.6.4 Discussion and Conclusions on triaxially gained VCLs It was possible to determine a VCL which is similar to the one gained from the in-situ approach. However, the approximate relationships of � 1, � 2 ,and� 3 as occurring from a tyre pass have to be maintained, because it was shown, that the slope and intercept of the VCL depends on that relationship. In general, a VCL is not unique to a given soil with given moisture content; it depends on the relationship of minor and major principal stresses. Overall comparing the success in predicting soil displacement from tyre passes the in-situ VCL achieved a higher accuracy than any triaxially gained VCL. For a rough estimation 131
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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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Field Study With Full Size Combine
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Page 95 and 96: Field Study With Full Size Combine
Page 97 and 98: Field Study With Full Size Combine
Page 99 and 100: Alleviation of Soil Compaction Howe
Page 101 and 102: Alleviation of Soil Compaction not
Page 103 and 104: Alleviation of Soil Compaction in a
Page 105 and 106: Alleviation of Soil Compaction diff
Page 107 and 108: Soil Compaction Models sibilities t
Page 109 and 110: Soil Compaction Models depends on t
Page 111 and 112: Soil Compaction Models Wroth (1968)
Page 113 and 114: Soil Compaction Models however, the
Page 115 and 116: Soil Compaction Models level. Criti
Page 117 and 118: Soil Compaction Models Utilizing Ke
Page 119 and 120: Soil Compaction Models average of m
Page 121 and 122: Soil Compaction Models Depth (mm) -
Page 123 and 124: Soil Compaction Models ture content
Page 125 and 126: Soil Compaction Models with four ot
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
Page 135 and 136: Soil Compaction Models VCL paramete
Page 137 and 138: Soil Compaction Models The approach
Page 139 and 140: Soil Compaction Models surface stay
Page 141 and 142: Soil Compaction Models This result
Page 143 and 144: Soil Compaction Models 6.6.1.3 Wate
Page 145: Soil Compaction Models σσ 1 (kPA)
Page 149 and 150: Soil Compaction Models The response
Page 151 and 152: Soil Compaction Models On medium so
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
Page 159 and 160: Ancillary Experiments In order to c
Page 161 and 162: Ancillary Experiments contrary, the
Page 163 and 164: Ancillary Experiments Figure 102: S
Page 165 and 166: Ancillary Experiments track and the
Page 167 and 168: Ancillary Experiments even when hav
Page 169 and 170: Ancillary Experiments 7.3.2 Influen
Page 171 and 172: Ancillary Experiments The results f
Page 173 and 174: Ancillary Experiments Figure 117: S
Page 175 and 176: Ancillary Experiments Contact Press
Page 177 and 178: Ancillary Experiments Figure 123: F
Page 179 and 180: Ancillary Experiments Sinkage (mm)
Page 181 and 182: Ancillary Experiments model which o
Page 183 and 184: Ancillary Experiments 7.3.5 The Inf
Page 185 and 186: Ancillary Experiments 7.3.7 Discuss
Page 187 and 188: Ancillary Experiments Terzaghi (194
Page 189 and 190: Ancillary Experiments contact area.
Page 191 and 192: Ancillary Experiments soil forward
Page 193 and 194: Conclusions � The longitudinal so
Page 195 and 196: 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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