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Soil Compaction Models the width of the tyre and half the contact length is plotted against measured rut depth in Figure 95. For reference plate sinkage parameters gained from the small scale experiment in the triaxial cell are included. Figure 96 contains the large plate sinkage predictions and compares it to the predicted rut depth using COMPSOIL. Predicted Depth (mm) 500 450 400 350 300 250 200 150 100 50 0 Dense Medium Loose Real Contact Width 1:1 Line Half Contact Length Triaxial Fast Real Width Triaxial Fast, Half Length Linear 1:1 Line (1:1 Line) 0 50 100 150 200 250 300 350 Measured Depth (mm) Figure 95: Predicted vs. measured depth of the tyres from plate sinkage data The predicted and measured rut depths for the dense and medium soil condition show tol- erable deviation in Figure 95, whereby using the tyre width for the shortest contact length results in a slightly underpredicted sinkage compared to using half the contact length which results in a slightly overpredicted rut depth. However, on soft soil conditions, the deviation is about 100 %. This might be due to the fact that the Bekker model assumes an infinite soil depth below, whereas in the soil bin, the maximum depth is 750 mm. Predicted Rut Depth Depth (mm) (mm) 500 450 400 350 300 250 200 150 100 50 0 Dense Medium Loose Real Contact Width Half Contact Length COMPSOIL 1:1 Line Linear 1:1 Line (1:1 Line) 0 50 100 150 200 250 300 350 Measured Rut Depth (mm) Figure 96: Predicted vs. measured depth of the tyres from plate sinkage data and from COMPSOIL Ph.D. Thesis Dirk Ansorge (2007) 134
Soil Compaction Models On medium soil conditions, the results could be replicated using the plate sinkage data gained from small scale contact patches in the triaxial test apparatus as described in 2.3.2. This shows that plate sinkage tests can be used for both the estimation of in-situ VCL parameters and Bekker-parameters. A mathematical justification of this was given by Sime and Upadhyaya (2004) and is explained in Section 6.7. The advantage of the Bekker approach is, that its parameters can be measured much easier than critical state soil mechanics or VCL parameters, however, the technique still requires plate sinkage tests performed to gain the parameters. Therefore the assessment is not as straight forward as the one proposed in Section 6.3.1 with the in-situ VCL whereby the measurements can be taken from rut depths created by tyres. Figure 96 shows that the predicted rut depths from COMPSOIL are intermediate between the Bekker approach utilizing the contact width and the one using half the contact length. From this it can be concluded that overall COMPSOIL predicts rut depths closer to the measured data, particularly on the soft soil. 6.8.2 Sinkage of Tracks The track sinkage equation of Bekker (1960) “Track” could possibly be utilized to explain the different behavior of different tracks. However, as it assumes n to be equal to 1 which is only the case on very soft soils the predicted sinkage in Table 27 needs to be considered with care. The elastic elongation of the track (Slag) is taken into account with the “Track” equation. Besides the “Track” Table 27 includes the predictions of track sinkage gained directly from the plate sinkage approach “Plate”. Additionally the Bernstein equation (Bernstein, 1913) is included: 6* W z � 5* r * b * k * D Eq. 7 whereby r is the number of rollers in the track unit and D is equal to the diameter of the largest roller of the track unit. According to Table 27 the general plate sinkage equation would predict sinkages too small. With “Track” assuming a slag of 0.02 sinkage is estimated too high in a range of 2 – 9 mm Ph.D. Thesis Dirk Ansorge (2007) 135
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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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Page 99 and 100: Alleviation of Soil Compaction Howe
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Page 103 and 104: Alleviation of Soil Compaction in a
Page 105 and 106: Alleviation of Soil Compaction diff
Page 107 and 108: Soil Compaction Models sibilities t
Page 109 and 110: Soil Compaction Models depends on t
Page 111 and 112: Soil Compaction Models Wroth (1968)
Page 113 and 114: Soil Compaction Models however, the
Page 115 and 116: Soil Compaction Models level. Criti
Page 117 and 118: Soil Compaction Models Utilizing Ke
Page 119 and 120: Soil Compaction Models average of m
Page 121 and 122: Soil Compaction Models Depth (mm) -
Page 123 and 124: Soil Compaction Models ture content
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)
Page 147 and 148: Soil Compaction Models pressure to
Page 149: Soil Compaction Models The response
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 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
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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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