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Soil Compaction Models where z is the depth (m), A is the contact area (m 2 ) and � is the concentration factor. c1, c2, and c3 are constants whose values are given in the Appendix and depend on the calculated stress ratio. To calculate � 2 and � 3 Eq. 6 would have to be solved for all tyres at each depth within the soil. To simplify the approach a depth z of 0.4 m representing the average depth in the soil profile and a contact area A of 0.8 m 2 were assumed and � was varied from three to five representing possible soil conditions (dense to soft) as proposed by Fröhlich (1934). The resulting dependencies of � 2 and � 3 on � 1 are given in Appendix 11.1.2.2. In a first approximation � = 5 was chosen to calculate p from the contact pressures given in Table 26 of the treatments by Ansorge (2005, a) and this study. Knowing the initial density of 1.38 g/cm 3 and the average increase, final density can be calculated. Relative density (RD) is gained by dividing final dry bulk density (Final DBD) into 2.66 g/cm 3 . The average increase (AvI), the final DBD and RD are also given in Table 26. Table 26: Treatments and corresponding increase in DBD, final DBD, relative DBD Treatment (Section width[mm]/Load [t]/Inflation Pressure [bar]) and � 2 and � 3 , contact pressure and mean normal pressure for � = 5 AvI (%) Final DBD (g/cm 3 ) Ph.D. Thesis Dirk Ansorge (2007) RD � 2 + � 3 (kPa) Contact Pressure ( � 1 ) (kPa) 900/5/0.5 5.66 1.458 1.817 29 76 35 500-70/4.5/2.3 14.27 1.577 1.681 54 142 65 500-85/4.5/1.4 11.06 1.533 1.729 42 110 51 600/4.5/1.4 11.00 1.532 1.730 43 114 52 700/4.5/1.0 10.59 1.526 1.736 36 96 44 900/10.5/1.9 17.30 1.619 1.637 43 112 52 800/10.5/2.5 17.36 1.620 1.636 64 169 78 800/10.5/1.25 11.59 1.540 1.721 41 107 49 680/10.5/2.2 17.73 1.625 1.631 58 152 70 Roller 1.380 1.928 22 58 26 Figure 70 shows relative density vs. mean normal pressure. A logarithmic regression line was fitted to the data points representing the in-situ VCL for the sandy loam soil at a mois- 106 P (kPa)
Soil Compaction Models ture content of approximately 9 % at which the experiments were conducted. The VCL for the sandy loam soil given by O’Sullivan et al. (1998) is also included for reference. Rel. Density 3 2,5 2 1,5 1 0,5 0 y = -0,2432Ln(x) + 2,6726 R 2 =0,8698 y =-0,123Ln(x) +2,4221 R 2 =1 10 100 1000 Pressure (kPa) Figure 70: Virgin compression line for sandy loam soils ■ from O’Sullivan et al. (1998) and ♦ from the soil bin studies based on the average density increases from Ansorge and Godwin (2007a) The intercept and slope of the in-situ VCL were used in COMPSOIL. The prediction per- formed with these modified parameters is compared to the measured data in Figure 71 for six individual tyres and close general agreement was achieved. Soil displacement is suc- cessfully predicted using COMPSOIL and the parameters of the in-situ VCL obtained from the soil bin experiments with a heuristically chosen concentration factor of � =5 suits best. The effect of other � is evaluated in Appendix 11.1.2.2. Fitting linear regression functions through the top 500 mm of the measured and predicted data of Figure 71 estimating the average increase in soil density as described by Ansorge and Godwin (2007a) and plotting the measured against predicted average density increase results in close agreement as shown in Figure 72 to within +/- 2 % errors. The data is spread randomly around the line of slope 1 and does not exhibit a general offset confirming the choice of � = 5. Fitting a linear regression line shows a marginal overprediction of 0.8% and the R 2 = 0.85 confirms the overall effectiveness of the technique. Ph.D. Thesis Dirk Ansorge (2007) 107
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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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Page 71 and 72: Laboratory Studies Into Undercarria
Page 77 and 78: Field Study With Full Size Combine
Page 99 and 100: Alleviation of Soil Compaction Howe
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Page 107 and 108: Soil Compaction Models sibilities t
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Page 111 and 112: Soil Compaction Models Wroth (1968)
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Page 117 and 118: Soil Compaction Models Utilizing Ke
Page 119 and 120: Soil Compaction Models average of m
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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 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
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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
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Ancillary Experiments 7.3.7 Discuss
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Ancillary Experiments Terzaghi (194
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Ancillary Experiments contact area.
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Ancillary Experiments soil forward
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Conclusions � The longitudinal so
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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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