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Laboratory Studies Into Undercarriage Systems Rectangularity 0,8 0,7 0,6 0,5 0,4 0,3 0,2 0,1 0 Terra Trac Westtrack Stocks SPT Tire Figure 44: Rectangularity for different track units Pressure (bar) 3 2,5 2 1,5 1 0,5 0 Terra Trac Westtrack Stocks SPT Tire Figure 45: Pressure summary for different track units 3.3.2.4 Rut Parameters for Belt Tension and Track Evaluation Contact Pressure Peak Pressure Average Peak Average Valley The rut parameters for both the influence of belt tension and the comparison of tracks are given in Table 11. Table 11: Rut parameters for track evaluation Treatment Area (m 2 ) Max. Rut Width (m) Max. Rut Depth (m) Stocks 0.052 a 0.85 a 0.094 a SPT 0.062 b 0.87 b 0.127 b Westtrack 0.049 a 0.82 c 0.090 a TerraTrac 50 bar 0.039 c 0.68 d 0.090 a TerraTrac 160 bar 0.033 d 0.68 d 0.075 c TerraTrac 200 bar 0.031 d 0.69 d 0.078 c LSD 0.0041 0.018 0.006 Ph.D. Thesis Dirk Ansorge (2007) 56
Laboratory Studies Into Undercarriage Systems The width of the different units depended on the belt width. The TerraTrac had a belt width of 635 mm whereas all other units ran with 750 mm wide belts. This had the consequence that the rut area for these treatments was bigger. The rut depth corresponded to some extent to the results of the soil displacement measurements. For the TerraTrac unit max rut depth and rut area were smallest compared to Stocks, SPT, and Westtrack although no difference was apparent from soil displacement measurement. The TerraTrac at 50 bar belt tension created as well a significantly deeper maximum rut depth and larger rut area than at 160 and 200 bar. 3.3.2.5 Discussion and Conclusions The performance of the Stocks and Westtrack units compared to the TerraTrac unit could be attributed to the wider belt. The wider belt enabled them to reduce contact time while maintaining similar contact pressures. Yet, contact time could not be the mere reason as both, the Stocks and SPT unit, had 0.68 s less contact time than the TerraTrac unit, however, the soil displacement below the SPT unit was highest. A smooth pressure distribution is essential. The more rollers there were in a track unit and the closer together these rollers were, the more uniform became the pressure application as demonstrated by the Stocks unit. If the TerraTrac unit was equipped with the wider belt of the other units, it would most likely outperform them. Although the previous section could not show a large effect of belt tension on soil physical parameters for a friction driven rubber track system, the low belt pressure of the SPT is an additional reason for its larger impact on soil physical properties. This is in accordance with Wong’s (2007) requirement for high belt tension and reasonable roller distribution. The Appendix contains a brief theoretical background of sinkage caused by tracks applying Bekker (1960). For track development it can be concluded that there is an optimum amount of rollers. Too few rollers are disadvantageous as the Stocks unit outperforms SPT. But above a treshhold value, the benefit from additional rollers becomes marginal (comparison of Stocks to the Westtrack unit) which agrees with Wong (2001) and Bekker (1960). Ph.D. Thesis Dirk Ansorge (2007) 57
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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
Page 21 and 22: Introduction 1.2 Aim To elucidate t
Page 23 and 24: Introduction a) the soil compaction
Page 25 and 26: Experimental Methods 2.1.1.1 Test F
Page 27 and 28: Experimental Methods had been mount
Page 29 and 30: Experimental Methods track; the loa
Page 31 and 32: Experimental Methods 800/10.5/2.5 t
Page 33 and 34: Experimental Methods term. In the m
Page 35 and 36: Experimental Methods Soil Surface F
Page 37 and 38: Experimental Methods Depth (cm) 0 1
Page 39 and 40: Experimental Methods ence surface c
Page 41 and 42: Experimental Methods chine derives
Page 43 and 44: Experimental Methods depth. The dat
Page 45 and 46: Experimental Methods with water and
Page 47 and 48: Experimental Methods 2.4 Statistica
Page 49 and 50: Laboratory Studies Into Undercarria
Page 71: Laboratory Studies Into Undercarria
Page 77 and 78: Field Study With Full Size Combine
Page 99 and 100: Alleviation of Soil Compaction Howe
Page 101 and 102: Alleviation of Soil Compaction not
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) -
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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
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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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