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Conclusions 8 CONCLUSIONS � The benefit of tracks with respect to reduced soil displacement, penetrometer resis- tance, rut depth, and density increase shown by Ansorge (2005, a) is maintained for entire machine configurations after the additional passage of the rear axle in both laboratory and field studies. � Alternative wheel configurations could reach the performance of tracks if the tyre load does not exceed 5 t. It was shown that a combine harvester equipped with Ter- raTracs at a total weight of 33 t maintains soil displacement similar to that of a wheeled combine harvester of one third of the weight The track at 2.67 times the load of a tyre causes similar soil displacement. � The superiority of the tracks towards additional soil displacement caused by the rear tyres could be attributed to the dense layer created at the soil surface. � The differences between different tracks can be attributed to the number of rollers and belt tension as they can significantly affect soil displacement. However, the ef- fect of belt tension of the friction driven TerraTrac on soil physical properties proved to be small within the range of belt tensions available. � The draught force necessary to loosen soil after the passage of a wheeled machine is significantly higher than after a tracked machine and can reach a factor of 3 if the additional working depth resulting from deeper reaching higher compaction after a wheel is taken into consideration. � An in-situ method was developed to gain the slope and intercept of a virgin com- pression line basically from 2 different tyre passes in the field with known weight, inflation pressure and rut depth. Using these in-situ VCL parameters in the model COMPSOIL of O’Sullivan et al. (1998) it was possible to predict the input data and independent data within the LSD. The entire method was successfully validated in field conditions and small scale plate sinkage tests. � Soil density increase after the passage of tracks could be predicted using a track specific in-situ VCL. Hence, it became obvious that tracks show a different compaction behavior than tyres. � Triaxially derived VCLs are sensitive to the relationship of major and minor princi- pal stresses. Only if their relationships replicates true field conditions, a suitable VCL for soil compaction prediction can be gained. Ph.D. Thesis Dirk Ansorge (2007) 176
Conclusions � The longitudinal soil movement below a track is tilted significantly backwards whereas the soil is tilted forward below a tyre in low slip applications. In both cases this movement is limited to the top 150 mm in weak soil conditions. � The influence of lugs on variation in soil displacement is limited to a depth of ap- proximately 150 mm. � Load per perimeter length appeared to describe measured increase in DBD more accurately than contact pressure alone. Soil density increase for individual treat- ments could be described by the reciprocal of three trems: area, perimeter, and an interaction term. The intercept was not significant which means that there is no off- set. Hence, it has been possible to define the sinkage from a tyre contact area per- spective. � Peak pressures replicating the pass of a tyre cause 1/3 more sinkage than the appli- cation of the constant average pressure. � The vertical “punching” soil failure found in the laboratory studies supports the findings of Seig (1985) and others and can be explained by both plate sinkage theory (Benoit and Gotteland, 2005) and passive earth pressure theory. Ph.D. Thesis Dirk Ansorge (2007) 177
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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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Alleviation of Soil Compaction Howe
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Alleviation of Soil Compaction not
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Alleviation of Soil Compaction in a
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Alleviation of Soil Compaction diff
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Soil Compaction Models sibilities t
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Soil Compaction Models depends on t
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Soil Compaction Models Wroth (1968)
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Soil Compaction Models however, the
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Soil Compaction Models level. Criti
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Soil Compaction Models Utilizing Ke
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Soil Compaction Models average of m
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Soil Compaction Models Depth (mm) -
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Soil Compaction Models ture content
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Soil Compaction Models with four ot
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Soil Compaction Models Predicted In
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Soil Compaction Models Depth (mm) -
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Soil Compaction Models and 13.7 % b
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Soil Compaction Models Rel. Density
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Soil Compaction Models VCL paramete
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Soil Compaction Models The approach
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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 and 146: Soil Compaction Models σσ 1 (kPA)
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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: Ancillary Experiments soil forward
Page 195 and 196: Bibliography 10 BIBLIOGRAPHY Aboaba
Page 197 and 198: Bibliography Defossez, P., Richard,
Page 199 and 200: Bibliography Gregory, A.S.; Whalley
Page 201 and 202: Bibliography Lamande, M., Schjonnin
Page 203 and 204: Bibliography Seig, D., 1985. Soil C
Page 205 and 206: Appendix 11 APPENDIX Ph.D. Thesis D
Page 207 and 208: Appendix Figure 32: VCL sample at t
Page 209 and 210: Appendix comparison at the deepest
Page 211 and 212: Appendix Estimated Pressure (kPa) 2
Page 213 and 214: Appendix 11.1.1.2.1 SOCOMO One of t
Page 215 and 216: Appendix by Seig (1985) who showed
Page 217 and 218: Appendix Soil water content 15 % an
Page 219 and 220: Appendix Adapting critical state so
Page 221 and 222: Appendix density is obtained by add
Page 223 and 224: Appendix Table 5: Values of constan
Page 225 and 226: Appendix choice of a concentration
Page 227 and 228: Appendix 11.1.3.1 Dense/Hard and Lo
Page 229 and 230: Appendix 11.1.3.2 Stratified Soil C
Page 231 and 232: Appendix To summarize the ability t
Page 233 and 234: Appendix In the following the predi
Page 235 and 236: Appendix concentration factor of 4,
Page 237 and 238: Appendix 11.1.5.1 Confining Pressur
Page 239 and 240: Appendix Figure 24. The VCL created
Page 241 and 242: 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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