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Appendix more pressure is necessary. A decreased intercept means less pressure for the same DBD, too. With an increased intercept the opposite is true. In Table 4 the functionality of critical soil mechanics parameters and their implications on the predicted results is summarized. This aims on investigating whether a change in critical state soil mechanics parameters will get the predictions of the model closer to the range of the real results. Table 4 shows the given parameters and their corresponding maximum predicted DBD, whereby the increase of the DBD is given at the surface and at depth, too. Predicted rut depth is shown, too. In a first step the slope of the virgin compression line was reduced which in consequence reduced soil compaction as expected. With a reduction in the intercept soil compaction increased significantly. With a slope of about 0.15 the results came into the range measured in the soil bin by Ansorge (2005). The recompression lines were not changed because their influence can be ignored as they influence the response to multiple loadings and have no impact on single passes which are investigated at this stage. Table 4: Variation in predicted soil compaction with changes in critical state soil Slope Y Axis mechanics parameters Recompression lines Final max.DBD [g/cm 3 ] Increase top Ph.D. Thesis Dirk Ansorge (2007) [%] Increase Bottom 0.123 2.422 0.0087/0.0327 1.41 3 0 12 0.1 2.422 0.0087/0.0327 1.39 1 3 0.123 2.0 0.0087/0.0327 1.80 43 25 250 0.15 2.422 0.0087/0.0327 1.51 12 3 45 0.123 3.0 0.0087/0.0327 1.38 0 0 0 0.15 2.422 0.008/0.0327 1.51 13 3 50 0.15 2.422 0.0095/0.0327 1.50 12 3 45 0.15 2.422 0.0087/0.025 1.51 12 2 45 0.15 2.422 0.0087/0.04 1.51 12 4 50 [%] 201 Rut depth Changing critical state soil parameters to fit the data seems a promising way to make the data fit existing soil mechanics models. 11.1.1.2.3 Conclusion and Outlook The comparison of measured pressure to calculated pressure showed some deviation, yet the magnitude is too small to explain the large differences seen especially in COMPSOIL. [mm]
Appendix Adapting critical state soil parameters to fit the data seems a promising way to make the data fit existing soil mechanics models. An approach to gain information about the virgin compression line is to investigate the slope of the soil displacement curves from this work and the work by Ansorge (2005). The virgin compression line basically describes the reciprocal of soil density in dependence of exerted stress. The corresponding contact pressure can be assigned to the slope of each soil displacement curve by calculating the stress below a tyre from the known area and known load, assuming uniform stress distribution over the contact area. This contact pressure is in some relation to the exerted stress for the VCL model. As in detail explained by Ansorge and Godwin (2007a) from the slope of a soil displacement line the corresponding increase in soil density can be gained. Knowing the initial soil stress exerted by the roller during soil bin preparation and knowing the resulting initial soil density gives the first point on the virgin compression line. Knowing the increase in density for different contact pressures the virgin compression line can be created and the recompression line could be gained from multi passes. If in a future step it was further possible to determine the virgin compression line just from tyre sinkage at two different inflation pressures, a very important characteristic of soil compaction could easily be determined in the field. 11.1.2. Derivation of VCL Parameters from Soil Bin and Validation/Evaluation In a first step this “in-situ virgin compression line” will be created utilizing the different treatments from the soil bin. The approach will be validated in-field conditions, too. After gaining the slope and intercept of the virgin compression line, these parameters will be traditionally verified in a pressure cell. 11.1.2.1 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, bulk density and moisture content data whereby COMPSOIL assumes VCL parameters. An initial comparison of soil displacement measured by Ansorge 2005 on a sandy loam to the data predicted by COMPSOIL using the virgin compression line (VCL) parameters suggested Ph.D. Thesis Dirk Ansorge (2007) 202
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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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Page 175 and 176: Ancillary Experiments Contact Press
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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: Appendix Soil water content 15 % an
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
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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
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Page 253 and 254: Appendix � z � � �� k c p
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Page 259 and 260: Appendix with a slight deviation fr
Page 261: Appendix Table 12: DBD values for a
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