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Alleviation of Soil Compaction Spec. Draught force and loosend area follow in general the equations: Loosened Area = a * Working Depth b Spec.Draught Force = c * Working Depth Eq. 4 whereby a, b, and c are empirically determined constants; i.e. for a sandy loam soil in this condition the values are approximately 1.4, 1.15, and 0.1-0.4, respectively. The linear relationship between working depth and spec. draught force was mentioned by Spoor and Godwin (1978).Eq. 4 can be substituted in Eq. 3 to express absolute draught force depending on working depth. From the profiles gained in the experiment the loosened area was estimated if the subsoiler tine ran 100 mm deeper. This gave three data points for each the track and the tyre enabel- ing the fit of a regression curve to determine the relationship of depth to loosened area. Knowing from Spoor and Godwin (1978) that specific draught force increases linearly with depth, the single draught force measurement for each treatment in section 5.2 was suffi- cient to derive a regression line. It was possible to determine the following graph showing absolute draught force depending on working depth by substituting these empirically gained equations into Eq. 3: Draft Force (kN) 45 40 35 30 25 20 15 10 5 0 0 100 200 300 400 500 600 Depth (mm) Ph.D. Thesis Dirk Ansorge (2007) Tyre Track Figure 63: Draught force vs. depth for a subsoiler tine after the pass of a tracked and a wheeled combine harvester From the penetrometer resistance for different undercarriage systems in Figure 28 the appropriate working depth on such a loose soil to alleviate the compaction caused by the pass of a combine harvester was set to 350 mm for the track as here the shape of the curve did 84
Alleviation of Soil Compaction not change quickly anymore. For the tyre it was set to 450 mm as this is the maximum working depth commonly used and it is difficult to find equipment to work at greater depths. Going back into Figure 63 the chosen working depth of 350 mm for a track and 450 for a tyre resulted in 10 kN and 27 kN draught force, respectively. For practical calculations the following assumptions were made: � Loosening both wheel/track marks in one go => doubling the above draught force � Approximately 1600 m track length per ha assuming a cutterbar width of 7.5 m and field efficiency of 0.83 � Working speed for subsoiling 2 m/s or 7.2 km/h Knowing the required draught force the appropriate tractor weight can be calculated. For sustained working a slip � of 13 % should not be exceeded resulting in a draught to weight ratio � of 0.35 for a dry stubble field (Kutzbach, 2003). Therefore the weight of the machine has to be 1/0.35 times the required draught force. With the required draught force of 2*10 kN and 2*27kN, respectively, the tractor pulling the subsoiler after the tracked combine harvester has to weigh 57 kN and after the wheeled combine 154 kN. The efficiency of the whole tractor is the product of the efficiency of the transmission and the draught efficiency � . With the given slip � and draught to weight ratio � � results from: � � � * 1� � � � � � � Eq. 5 With the numbers from above � becomes 0.72. Gear box efficiency can be assumed to be about 0.85 (Kutzbach, 2003). Hence total efficiency results in 0.612. Running at 2 m/s, a tractor efficiency of 0.612 and a draught force requirement of 2*10 kN for the tracked and 2*27 kN for the wheeled machine results in power requirements of 65.4 kW and 176.5 kW, respectively. In Table 24 the tractor requirements are summarized. Ph.D. Thesis Dirk Ansorge (2007) 85
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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
Page 49 and 50: Laboratory Studies Into Undercarria
Page 77 and 78: Field Study With Full Size Combine
Page 99: 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 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 and 150: 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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