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Appendix Depth (mm) -100 0 100 200 300 400 500 600 700 5 Both 5 Subsoil 4 Both 4 Subsoil 5 Shallow 4 Shallow Soil Bin VCL Depth (mm) -10 0 10 20 30 40 50 6 0 70 80 -10 -10 0 0 10 20 30 40 40 50 60 60 70 70 80 80 Displacement (mm) Displacement (mm) Ph.D. Thesis Dirk Ansorge (2007) -100 0 100 200 300 400 500 600 700 5 Both 5 Subsoil 4 Both 4 Subsoil 5 Shallow 4 Shallow Soil Bin VCL Figure 21: Measured (points) and predicted (lines) soil displacement for the normal (2.5 bar) (left hand side) and high inflation pressure (3.5 bar) (right hand side) treatment on subsoiled sandy loam Overall it seems as if a concentration factor of 5 seems appropriate to describe the pressure propagation for a sandy loam soil and a concentration factor of 4 to describe a clay soil. This can be explained from their different particle size distribution which overall gives the sandy loam a coarser network compared to the clay which is due to the smaller particle sizes much finer. Due to the finer network the pressure decreases less with depth and is transmitted to deeper layers more easily than with the coarser network of a sandy soil. In future work consideration should be given to the behaviour of tyre contact patches at different inflation pressures when they vary from the recommended inflation pressure either positively or negatively as in either case prediction results are not satisfactory. 11.1.5 Triaxial Justification of VCL In this section the soil bin approach to gain a VCL will be evaluated by gaining an adequate VCL with a triaxial test equipment. Initially confining pressure will be applied followed by an investigation of the water compressibility and finally axial and radial pressure will be applied trying to mimic real soil bin conditions. At the end all the different prediction results of the varying VCLs will be compared. In Appendix 1.6 the soil bin approach to gain a VCL will be taken by utilizing small scale plate sinkage tests rather than tyres. 219
Appendix 11.1.5.1 Confining Pressure Applied In the first sequence only confining pressure was applied as this is the commonly referred way in literature to gain a virgin compression line according to Leeson and Campbell (1983). In the second subchapter a higher axial stress will be applied. 11.1.5.1.1 Influence of Time of Loading In the first set of tests only confining pressure was applied to the soil samples. The samples were loaded to 100 kPa, unloaded and then reloaded up to 250 kPa. The short loading time from the soil bin can not be repeated because cell pressure can not be changed instantaneously. The influence of loading time on virgin compression parameters was investigated by allowing the system different amounts of time to reach each set pressure. Figure 22 shows the results from the experiments with different time spans used for loading. The different starting points at the beginning are due to slightly different initial densities. However, the curves merge at approximately 100 kPa indicating that differences in initial density do not affect the final results which agrees with the theory. The shortest loading time allowed 30 min to reach the set pressure, the medium loading time allowed 120 min to reach each set pressure and the slow curve was allowed 360 min to reach the maximum pressure. As obvious from the diagram there are no differences amongst the treatments and no clear tendency with loading time is visible either. Natural variation has a larger influence than the allowed time scale. This is shown with the slow VCL, which is expected to be the weakest due to the amount of time allowed to compact, but on the contrary, it is in fact the strongest. Rel. Density 2,1 2 1,9 1,8 1,7 VCL FAST 4th Testday 1,6 VCL 1 DENSE 4th Testday 1,5 VCL Medium 4th Testday VCL1 Slow 1,4 O'Sullivan 1,3 Full Pressure 1,2 1 0.38 Pressure 10 100 1000 Mean Normal Pressure (kPa) Figure 22: The influence of loading time on the shape of virgin compression lines and virgin compression lines from tyre data (pressure) and from literature (O’Sullivan et al, 1998) Ph.D. Thesis Dirk Ansorge (2007) 220
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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
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Soil Compaction Models This result
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Soil Compaction Models 6.6.1.3 Wate
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Soil Compaction Models σσ 1 (kPA)
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Soil Compaction Models pressure to
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Soil Compaction Models The response
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Soil Compaction Models On medium so
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Soil Compaction Models SOILFLEX tak
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Ancillary Experiments 7 ANCILLARY E
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Ancillary Experiments Average conta
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Ancillary Experiments In order to c
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Ancillary Experiments contrary, the
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Ancillary Experiments Figure 102: S
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Ancillary Experiments track and the
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Ancillary Experiments even when hav
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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
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
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: Appendix concentration factor of 4,
Page 239 and 240: Appendix Figure 24. The VCL created
Page 241 and 242: Appendix Rel. Density 2 1,9 1,8 1,7
Page 243 and 244: Appendix relation of � 1 to � 2
Page 245 and 246: Appendix Rel. Density 2 1,9 1,8 1,7
Page 247 and 248: Appendix Rel. Density 1,7 1,68 1,66
Page 249 and 250: Appendix Depth (mm) 0,0 100,0 200,0
Page 251 and 252: Appendix Figure 42: Plate in cookin
Page 253 and 254: Appendix � z � � �� k c p
Page 255 and 256: Appendix Table 8: n and k depending
Page 257 and 258: Appendix to the plate sinkage equat
Page 259 and 260: Appendix with a slight deviation fr
Page 261: Appendix Table 12: DBD values for a
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