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Appendix Table 2: Pressure measured and predicted with Soil Flex using O’Sullivan (1998) surface approach or Keller (2005) approach Treatment Depth (mm) O’Sullivan (1998) in Soil Flex (kPa) Keller (2005) approach in Soil Flex (kPa) 800/10.5/2.5 250 219 276 160 800/10/2 250 199 253 118 800/10/2 400 167 194 88 800/10/2/ 650 110 118 50 800/10/1 250 148 198 96 800/10/1 400 131 166 53 800/10/1 650 94 109 32 Plane Strain 800/10.5/2.5 250 219 276 160 800/10/2 250 199 253 118 800/10/2 400 167 194 88 800/10/2/ 650 110 118 50 800/10/1 250 148 198 96 800/10/1 400 131 166 53 800/10/1 650 94 109 32 Ph.D. Thesis Dirk Ansorge (2007) 195 Measured Stress Varying Concentration Factors (c) for 800/10.5/2.5 treatment (c=5 standard) c = 3 250 209 257 160 c = 4 250 191 228 160 c = 6 250 225 289 160 11.1.1.2 Sensitivity Analysis of Soil Compaction Models The small differences in predicted stress propagation from the previous section cannot be the reason for the significant differences between predicted and measured soil deformation found by Ansorge (2005). This raises the question as to whether the default initial soil parameters used by the models are appropriate for the given soil type and conditions. Consequently a sensitivity analysis of SOCOMO and COMPSOIL will be conducted. (kPa)
Appendix 11.1.1.2.1 SOCOMO One of the most important parameters determining soil compaction is the value of preconsolidation stress in the soil for the SOCOMO model (van den Akker, 2004). Preconsolidation stress is the amount of stress a soil can carry without further permanent compaction, i.e. the soil responds elastically up to this stress. For a detailed explanation of preconsolidation stress see Ansorge (2005) or Gregory et al. (2006). Preconsolidation stress or structural strength was set to 200 kPa for the modeling undertaken by Ansorge (2005). This value shows sufficient agreement compared with the experimentally determined values of preconsolidation stress for sandy loam in the soil bin by Alexandrou (1995) who for DBD values between 1.35 – 1.38 g/cm 3 and a gravimetric moisture content of approximately 12 % determined an average preconsolidation stress of 236 kPa with a standard deviation of 69 kPa. Both angle of internal friction and cohesion were set to the specific values for the soil in soil bin laboratory. Therefore all parameters of the SOCOMO model represented real soil laboratory values. An increase in preconsolidation stress in the SOCOMO model for the 680 mm section width tyre and the 800 mm section width tyre at half inflation pressure, which were compared by Ansorge (2005), did not influence the area where initial soil strength was exceeded. In a subsequent step, first preconsolidation stress was increased to 250, 300, 400 and 600 kPa, respectively, and second initial DBD increased from 1.37 to 1.47 g/cm 3 . Neither changed the result. The result for a preconsolidation stress of 200 kPa is shown in Figure 3. A reduction in preconsolidation stress to 100 kPa changed the results for the output as shown in Figure 4. SOCOMO indicates the area where soil compaction happens with letters in a section perpendicular to the travel direction. The area stayed the same, yet the letters changed from P in Figure 3 to C and S closer to the surface in Figure 4. These letters did not appear before and are not explained in the model description. Therefore a personal discussion with van den Akker gave the following explanation. The letter P indicates only the excess of preconsolidation stress, the letter S indicates the excess of shear strength and C indicates the excess of both shear strength and preconsolidation stress. Therefore the results of SOCOMO seem resistant to higher preconsolidation stresses, although the soil bin soil was relatively weak and an increase in DBD accompanied by an increase in preconsolidation stress is expected to reduce soil displacement and as shown by Antille (2006). Ph.D. Thesis Dirk Ansorge (2007) 196
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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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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: Appendix Estimated Pressure (kPa) 2
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
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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