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Thomas Keller - One of the best experts on this subject based on the ideXlab platform.
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a model for prediction of vertical Stress distribution near the Soil surface below rubber tracked undercarriage systems fitted on agricultural vehicles
Soil & Tillage Research, 2016Co-Authors: Thomas Keller, Johan ArvidssonAbstract:Abstract Rubber-tracked vehicles are becoming increasingly popular in agriculture. Rubber-tracked undercarriage systems are typically fitted instead of tyres on heavy agricultural vehicles, with the aim of e.g. decreasing Soil Stress and Soil compaction risks. Therefore, accurate prediction of Soil Stresses below rubber-tracked systems is important. Here, we present a model for prediction of vertical Stress distribution at the rubber track–Soil interface. In the model, the rubber-tracked undercarriage system consists of a front and rear wheel (idler and drive wheel) and a number of support rollers. The Stress distribution in the longitudinal direction under a wheel or roller is described by harmonic oscillation, with the dynamic contact length being a function of wheel or roller diameter. In the lateral direction, the Stress distribution is modelled by a linear function, with the maximum Stress under the centre line of the track. Model input parameters include the load on the track, track width, track length (distance between front and rear axles), number of support rollers and wheel and roller diameter. The model, which is written in Visual Basic and implemented as a macro in an Excel spreadsheet, then computes the vertical Stress at the rubber track–Soil interface based on these inputs and the Stress distribution generated in the contact area can be used to simulate Soil Stresses. The model provides realistic estimates of the vertical Stress at the contact between rubber track and Soil, thereby improving predictions of Soil Stress and the compaction risks of rubber-tracked agricultural vehicles.
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transmission of vertical Soil Stress under agricultural tyres comparing measurements with simulations
Soil & Tillage Research, 2014Co-Authors: Thomas Keller, Markus Berli, Siul Ruiz, Mathieu Lamande, Johan Arvidsson, Per Schjonning, A P S SelvaduraiAbstract:Abstract The transmission of Stress induced by agricultural machinery within an agricultural Soil is typically modelled on the basis of the theory of Stress transmission in elastic media, usually in the semi-empirical form that includes the “concentration factor” (v). The aim of this paper was to measure and simulate Soil Stress under defined loads. Stress in the Soil profile at 0.3, 0.5 and 0.7 m depth was measured during wheeling at a water content close to field capacity on five Soils (13–66% clay). Stress transmission was then simulated with a semi-analytical model, using vertical Stress at 0.1 m depth estimated from tyre characteristics as the upper boundary condition, and v was obtained at minimum deviation between measurements and simulations. For the five Soils, we obtained an average v of 3.5 (for Stress transmitting from 0.1 to 0.7 m depth). This was only slightly different from v = 3 for which the elasticity theory-based classical solution of Boussinesq (1885) is satisfied. We noted that the estimated v was strongly dependent on (i) the reliability of Stress measurements, and (ii) the upper Stress boundary condition used for simulations. Finite element simulations indicated that the transmission of vertical Stresses in a layered Soil is not appreciably different from that seen in a homogeneous Soil unless very high differences in Soil stiffness are considered. Our results highlight the importance of accurate Stress readings and realistic upper model boundary conditions, and suggest that the actual Stress transmission could be well predicted according to the theory of elasticity for the conditions investigated.
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in situ subSoil Stress strain behavior in relation to Soil precompression Stress
Soil Science, 2012Co-Authors: Thomas Keller, Mathieu Lamande, Johan Arvidsson, Per Schjonning, Matthias Stettler, P WeisskopfAbstract:Soil compaction negatively influences many important Soil functions, including crop growth. Compaction occurs when the applied Stress, R, overcomes the Soil strength. Soil strength in relation to com- paction is typically expressed by the Soil precompression Stress, Rpc. Deformation is assumed to be elastic and reversible as long as R e Rpc. This work examined Soil Stress-strain behavior as measured in situ during wheeling experiments and related it to the Stress-strain behavior and Rpc measured on Soil cores in uniaxial compression tests in the laboratory. The data analyzed were from a large number of wheeling experiments carried out in Sweden and Denmark on Soils with a wide range of texture. Contradicting the concept of precompression Stress, we observed residual strain, ?res ,a tR e Rpc. These observations were supported by Stress-strain data measured in uniaxial compression tests, which likewise showed ?res 9 0a tR e Rpc. Residual strain was observed in the field whenR exceeded approximately 40 kPa, and when the ratio R/Rpc exceeded roughly 0.1, although ?res was very small at R/Rpc G 0.5. These values were similar to those obtained on confined uniaxial compression curves. On the basis of our findings, we question the use of Rpc as a measure of Soil strength and call for a reevaluation of the precompression Stress concept.
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challenges in the development of analytical Soil compaction models
Soil & Tillage Research, 2010Co-Authors: Thomas Keller, Mathieu Lamande, Thomas Keller, Mathieu LamandeAbstract:Abstract Soil compaction can cause a number of environmental and agronomic problems (e.g. flooding, erosion, leaching of agrochemicals to recipient waters, emission of greenhouse gases to the atmosphere, crop yield losses), resulting in significant economic damage to society and agriculture. Strategies and recommendations for the prevention of Soil compaction often rely on simulation models. This paper highlights some issues that need further consideration in order to improve Soil compaction modelling, with the focus on analytical models. We discuss the different issues based on comparisons between experimental data and model simulations. The upper model boundary condition (i.e. contact area and Stresses at the tyre–Soil interface) is highly influential in Stress propagation, but knowledge on the effects of loading and Soil conditions on the upper model boundary condition is inadequate. The accuracy of Stress transducers and therefore of Stress measurements is not well known, despite numerous studies on Stress in the Soil profile below agricultural tyres. Although arable Soils are characterised by distinct Soil layers with different mechanical properties, analytical models rely on a one-layer approach with regard to Stress propagation, an anomaly that needs further attention. We found large differences between Soil Stress–strain behaviour obtained from in situ measurements during wheeling experiments and those measured on cylindrical Soil samples in standard laboratory tests. We concluded that the main reason was differences in loading time, and suggest that future research should concentrate on in situ Stress–strain behaviour during short time, dynamic loading.
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Soil Stress as affected by wheel load and tyre inflation pressure
Soil & Tillage Research, 2007Co-Authors: Johan Arvidsson, Thomas Keller, Johan Arvidsson, Thomas KellerAbstract:Abstract The relative importance of wheel load and tyre inflation pressure on topSoil and subSoil Stresses has long been disputed in Soil compaction research. The objectives of the experiment presented here were to (1) measure maximum Soil Stresses and Stress distribution in the topSoil for different wheel loads at the same recommended tyre inflation pressure; (2) measure Soil Stresses at different inflation pressures for the given wheel loads; and (3) measure subSoil Stresses and compare measured and simulated values. Measurements were made with the wheel loads 11, 15 and 33 kN at inflation pressures of 70, 100 and 150 kPa. TopSoil Stresses were measured at 10 cm depth with five Stress sensors installed in disturbed Soil, perpendicular to driving direction. Contact area was measured on a hard surface. SubSoil Stresses were measured at 30, 50 and 70 cm depth with sensors installed in undisturbed Soil. The mean ground contact pressure could be approximated by the tyre inflation pressure (only) when the recommended inflation pressure was used. The maximum Stress at 10 cm depth was considerably higher than the inflation pressure (39% on average) and also increased with increasing wheel load. While tyre inflation pressure had a large influence on Soil Stresses measured at 10 cm depth, it had very little influence in the subSoil (30 cm and deeper). In contrast, wheel load had a very large influence on subSoil Stresses. Measured and simulated values agreed reasonably well in terms of relative differences between treatments, but the effect of inflation pressure on subSoil Stresses was overestimated in the simulations. To reduce Soil Stresses exerted by tyres in agriculture, the results show the need to further study the distribution of Stresses under tyres. For calculation of subSoil Stresses, further validations of commonly used models for Stress propagation are needed.
Johan Arvidsson - One of the best experts on this subject based on the ideXlab platform.
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a model for prediction of vertical Stress distribution near the Soil surface below rubber tracked undercarriage systems fitted on agricultural vehicles
Soil & Tillage Research, 2016Co-Authors: Thomas Keller, Johan ArvidssonAbstract:Abstract Rubber-tracked vehicles are becoming increasingly popular in agriculture. Rubber-tracked undercarriage systems are typically fitted instead of tyres on heavy agricultural vehicles, with the aim of e.g. decreasing Soil Stress and Soil compaction risks. Therefore, accurate prediction of Soil Stresses below rubber-tracked systems is important. Here, we present a model for prediction of vertical Stress distribution at the rubber track–Soil interface. In the model, the rubber-tracked undercarriage system consists of a front and rear wheel (idler and drive wheel) and a number of support rollers. The Stress distribution in the longitudinal direction under a wheel or roller is described by harmonic oscillation, with the dynamic contact length being a function of wheel or roller diameter. In the lateral direction, the Stress distribution is modelled by a linear function, with the maximum Stress under the centre line of the track. Model input parameters include the load on the track, track width, track length (distance between front and rear axles), number of support rollers and wheel and roller diameter. The model, which is written in Visual Basic and implemented as a macro in an Excel spreadsheet, then computes the vertical Stress at the rubber track–Soil interface based on these inputs and the Stress distribution generated in the contact area can be used to simulate Soil Stresses. The model provides realistic estimates of the vertical Stress at the contact between rubber track and Soil, thereby improving predictions of Soil Stress and the compaction risks of rubber-tracked agricultural vehicles.
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transmission of vertical Soil Stress under agricultural tyres comparing measurements with simulations
Soil & Tillage Research, 2014Co-Authors: Thomas Keller, Markus Berli, Siul Ruiz, Mathieu Lamande, Johan Arvidsson, Per Schjonning, A P S SelvaduraiAbstract:Abstract The transmission of Stress induced by agricultural machinery within an agricultural Soil is typically modelled on the basis of the theory of Stress transmission in elastic media, usually in the semi-empirical form that includes the “concentration factor” (v). The aim of this paper was to measure and simulate Soil Stress under defined loads. Stress in the Soil profile at 0.3, 0.5 and 0.7 m depth was measured during wheeling at a water content close to field capacity on five Soils (13–66% clay). Stress transmission was then simulated with a semi-analytical model, using vertical Stress at 0.1 m depth estimated from tyre characteristics as the upper boundary condition, and v was obtained at minimum deviation between measurements and simulations. For the five Soils, we obtained an average v of 3.5 (for Stress transmitting from 0.1 to 0.7 m depth). This was only slightly different from v = 3 for which the elasticity theory-based classical solution of Boussinesq (1885) is satisfied. We noted that the estimated v was strongly dependent on (i) the reliability of Stress measurements, and (ii) the upper Stress boundary condition used for simulations. Finite element simulations indicated that the transmission of vertical Stresses in a layered Soil is not appreciably different from that seen in a homogeneous Soil unless very high differences in Soil stiffness are considered. Our results highlight the importance of accurate Stress readings and realistic upper model boundary conditions, and suggest that the actual Stress transmission could be well predicted according to the theory of elasticity for the conditions investigated.
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in situ subSoil Stress strain behavior in relation to Soil precompression Stress
Soil Science, 2012Co-Authors: Thomas Keller, Mathieu Lamande, Johan Arvidsson, Per Schjonning, Matthias Stettler, P WeisskopfAbstract:Soil compaction negatively influences many important Soil functions, including crop growth. Compaction occurs when the applied Stress, R, overcomes the Soil strength. Soil strength in relation to com- paction is typically expressed by the Soil precompression Stress, Rpc. Deformation is assumed to be elastic and reversible as long as R e Rpc. This work examined Soil Stress-strain behavior as measured in situ during wheeling experiments and related it to the Stress-strain behavior and Rpc measured on Soil cores in uniaxial compression tests in the laboratory. The data analyzed were from a large number of wheeling experiments carried out in Sweden and Denmark on Soils with a wide range of texture. Contradicting the concept of precompression Stress, we observed residual strain, ?res ,a tR e Rpc. These observations were supported by Stress-strain data measured in uniaxial compression tests, which likewise showed ?res 9 0a tR e Rpc. Residual strain was observed in the field whenR exceeded approximately 40 kPa, and when the ratio R/Rpc exceeded roughly 0.1, although ?res was very small at R/Rpc G 0.5. These values were similar to those obtained on confined uniaxial compression curves. On the basis of our findings, we question the use of Rpc as a measure of Soil strength and call for a reevaluation of the precompression Stress concept.
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Soil Stress as affected by wheel load and tyre inflation pressure
Soil & Tillage Research, 2007Co-Authors: Johan Arvidsson, Thomas Keller, Johan Arvidsson, Thomas KellerAbstract:Abstract The relative importance of wheel load and tyre inflation pressure on topSoil and subSoil Stresses has long been disputed in Soil compaction research. The objectives of the experiment presented here were to (1) measure maximum Soil Stresses and Stress distribution in the topSoil for different wheel loads at the same recommended tyre inflation pressure; (2) measure Soil Stresses at different inflation pressures for the given wheel loads; and (3) measure subSoil Stresses and compare measured and simulated values. Measurements were made with the wheel loads 11, 15 and 33 kN at inflation pressures of 70, 100 and 150 kPa. TopSoil Stresses were measured at 10 cm depth with five Stress sensors installed in disturbed Soil, perpendicular to driving direction. Contact area was measured on a hard surface. SubSoil Stresses were measured at 30, 50 and 70 cm depth with sensors installed in undisturbed Soil. The mean ground contact pressure could be approximated by the tyre inflation pressure (only) when the recommended inflation pressure was used. The maximum Stress at 10 cm depth was considerably higher than the inflation pressure (39% on average) and also increased with increasing wheel load. While tyre inflation pressure had a large influence on Soil Stresses measured at 10 cm depth, it had very little influence in the subSoil (30 cm and deeper). In contrast, wheel load had a very large influence on subSoil Stresses. Measured and simulated values agreed reasonably well in terms of relative differences between treatments, but the effect of inflation pressure on subSoil Stresses was overestimated in the simulations. To reduce Soil Stresses exerted by tyres in agriculture, the results show the need to further study the distribution of Stresses under tyres. For calculation of subSoil Stresses, further validations of commonly used models for Stress propagation are needed.
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technical solutions to reduce the risk of subSoil compaction effects of dual wheels tandem wheels and tyre inflation pressure on Stress propagation in Soil
Soil & Tillage Research, 2004Co-Authors: Thomas Keller, Johan Arvidsson, Thomas Keller, Johan ArvidssonAbstract:Abstract The use of heavy machinery is increasing in agriculture, which induces increased risks of subSoil compaction. Hence, there is a need for technical solutions that reduce the compaction risk at high total machine loads. Three field experiments were performed in order to study the effects of dual wheels, tandem wheels and tyre inflation pressure on Stress propagation in Soil. Vertical Soil Stress was measured at three different depths by installing probes into the Soil horizontally from a dug pit. In one experiment, also the Stress distribution below the tyre was measured. Beneath the dual wheels, vertical Stresses at 0.15 and 0.3 m depth were lower between the two wheels than under the centre of each wheel, despite the gap between the wheels being small (0.1 m). At 0.5 m depth, vertical Stress beneath the wheels was the same as between the two wheels. The Stress interaction from the two wheels was weak, even in the subSoil. Accordingly, measured Stresses at 0.3, 0.5 and 0.7 m depth were highest under the centre of each axle centre line of tandem wheels, and much lower between the axles. For a wheel load of 86 kN, tyre inflation pressure significantly affected Stress at 0.3 m depth, but not at greater depths. Stress directly below the tyre, measured at 0.1 m depth, was unevenly distributed, both in driving direction and perpendicular to driving direction, and maximum Stress was considerably higher than tyre inflation pressure. Calculations of vertical Stress based on Boussinesq's equation for elastic materials agreed well with measurements. A parabolic or linear contact Stress distribution (Stress declines from the centre to the edge of the contact area) was a better approximation of the contact Stress than a uniform Stress distribution. The results demonstrate that Stress in the Soil at different depths is a function of the Stress on the surface and the contact area, which in turn are functions of wheel load, wheel arrangement, tyre inflation pressure, contact Stress distribution and Soil conditions. Soil Stress and Soil compaction are a function of neither axle load nor total vehicle load. This is of great importance for practical purposes. Reducing wheel load, e.g. by using dual or tandem wheels, also allows tyre inflation pressure to be reduced. This reduces the risk of subSoil compaction.
Xuanming Ding - One of the best experts on this subject based on the ideXlab platform.
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a modified analytical solution of Soil Stress distribution for xcc pile foundations
Acta Geotechnica, 2014Co-Authors: Yaru Lv, Anthony Gunawan, Charles Wang Wai Ng, Xuanming DingAbstract:X-section cast-in-place concrete pile (XCC pile) is a new type of pile foundation, which has an X-shaped cross section. Compared to the traditional circular pile of the same cross-sectional area, the bearing capacity of an XCC pile is higher due to increased cross-sectional perimeter. Since Geddes solution is based on St. Venant’s principle, leading to the results independent of the cross-sectional geometry and size, large differences are induced when estimating the Soil Stress distribution for XCC pile foundations. This paper derives a modified analytical solution, which is dependent on the cross-sectional geometry of XCC pile, from Geddes solution. Validation of this modified solution was conducted through three-dimensional numerical analysis and proven more suitable for XCC pile foundations. Parametric study on three geometrical parameters is conducted using this modified solution. The results indicate that the Stress in founding Soil due to skin friction decreases with increasing pile radius and central angle of concave, but increases with increasing length of flat side. The Stress due to end-bearing decreases with increasing pile radius and length of flat side, but increases with increasing central angle of concave. From the parametric studies, the recommended dimensions of XCC pile radius, length of flat side, and central angle of concave are recommended ranges from 200 to 600 mm, 30 to 60 mm, and 90° to 150°, respectively.
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field tests on bearing characteristics of x section pile composite foundation
Journal of Performance of Constructed Facilities, 2012Co-Authors: Hanlong Liu, Xuanming Ding, Gangqiang KongAbstract:AbstractTo investigate the behavior of X-section cast-in-place concrete piles (XCC pile), a series of static load tests for piled foundation are conducted on the basis of a soft Soil reinforcement engineering for a sewage treatment plant in the north of Nanjing, China. The testing results are presented in load-settlement curves, pile-Soil Stress ratios, distributions of skin friction (side friction) and axial force, and load-sharing between side resistance and end-bearing capacity. Comparative analysis between an XCC pile and a circular section concrete pile (circular pile) with the same cross-sectional area indicates that the XCC pile with its increased perimeter can improve the vertical-bearing capacity by 20% because of the larger skin friction. Also, the XCC pile shows increasing pile-Soil Stress ratio and reduces settlement. The existing design standards for traditional piles can be referenced by the XCC pile composite foundation, because the axial force and skin friction distribution are the same as...
Thomas Keller - One of the best experts on this subject based on the ideXlab platform.
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Soil Stress as affected by wheel load and tyre inflation pressure
Soil & Tillage Research, 2007Co-Authors: Johan Arvidsson, Thomas Keller, Johan Arvidsson, Thomas KellerAbstract:Abstract The relative importance of wheel load and tyre inflation pressure on topSoil and subSoil Stresses has long been disputed in Soil compaction research. The objectives of the experiment presented here were to (1) measure maximum Soil Stresses and Stress distribution in the topSoil for different wheel loads at the same recommended tyre inflation pressure; (2) measure Soil Stresses at different inflation pressures for the given wheel loads; and (3) measure subSoil Stresses and compare measured and simulated values. Measurements were made with the wheel loads 11, 15 and 33 kN at inflation pressures of 70, 100 and 150 kPa. TopSoil Stresses were measured at 10 cm depth with five Stress sensors installed in disturbed Soil, perpendicular to driving direction. Contact area was measured on a hard surface. SubSoil Stresses were measured at 30, 50 and 70 cm depth with sensors installed in undisturbed Soil. The mean ground contact pressure could be approximated by the tyre inflation pressure (only) when the recommended inflation pressure was used. The maximum Stress at 10 cm depth was considerably higher than the inflation pressure (39% on average) and also increased with increasing wheel load. While tyre inflation pressure had a large influence on Soil Stresses measured at 10 cm depth, it had very little influence in the subSoil (30 cm and deeper). In contrast, wheel load had a very large influence on subSoil Stresses. Measured and simulated values agreed reasonably well in terms of relative differences between treatments, but the effect of inflation pressure on subSoil Stresses was overestimated in the simulations. To reduce Soil Stresses exerted by tyres in agriculture, the results show the need to further study the distribution of Stresses under tyres. For calculation of subSoil Stresses, further validations of commonly used models for Stress propagation are needed.
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technical solutions to reduce the risk of subSoil compaction effects of dual wheels tandem wheels and tyre inflation pressure on Stress propagation in Soil
Soil & Tillage Research, 2004Co-Authors: Thomas Keller, Johan Arvidsson, Thomas Keller, Johan ArvidssonAbstract:Abstract The use of heavy machinery is increasing in agriculture, which induces increased risks of subSoil compaction. Hence, there is a need for technical solutions that reduce the compaction risk at high total machine loads. Three field experiments were performed in order to study the effects of dual wheels, tandem wheels and tyre inflation pressure on Stress propagation in Soil. Vertical Soil Stress was measured at three different depths by installing probes into the Soil horizontally from a dug pit. In one experiment, also the Stress distribution below the tyre was measured. Beneath the dual wheels, vertical Stresses at 0.15 and 0.3 m depth were lower between the two wheels than under the centre of each wheel, despite the gap between the wheels being small (0.1 m). At 0.5 m depth, vertical Stress beneath the wheels was the same as between the two wheels. The Stress interaction from the two wheels was weak, even in the subSoil. Accordingly, measured Stresses at 0.3, 0.5 and 0.7 m depth were highest under the centre of each axle centre line of tandem wheels, and much lower between the axles. For a wheel load of 86 kN, tyre inflation pressure significantly affected Stress at 0.3 m depth, but not at greater depths. Stress directly below the tyre, measured at 0.1 m depth, was unevenly distributed, both in driving direction and perpendicular to driving direction, and maximum Stress was considerably higher than tyre inflation pressure. Calculations of vertical Stress based on Boussinesq's equation for elastic materials agreed well with measurements. A parabolic or linear contact Stress distribution (Stress declines from the centre to the edge of the contact area) was a better approximation of the contact Stress than a uniform Stress distribution. The results demonstrate that Stress in the Soil at different depths is a function of the Stress on the surface and the contact area, which in turn are functions of wheel load, wheel arrangement, tyre inflation pressure, contact Stress distribution and Soil conditions. Soil Stress and Soil compaction are a function of neither axle load nor total vehicle load. This is of great importance for practical purposes. Reducing wheel load, e.g. by using dual or tandem wheels, also allows tyre inflation pressure to be reduced. This reduces the risk of subSoil compaction.
Johan Arvidsson - One of the best experts on this subject based on the ideXlab platform.
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Soil Stress as affected by wheel load and tyre inflation pressure
Soil & Tillage Research, 2007Co-Authors: Johan Arvidsson, Thomas Keller, Johan Arvidsson, Thomas KellerAbstract:Abstract The relative importance of wheel load and tyre inflation pressure on topSoil and subSoil Stresses has long been disputed in Soil compaction research. The objectives of the experiment presented here were to (1) measure maximum Soil Stresses and Stress distribution in the topSoil for different wheel loads at the same recommended tyre inflation pressure; (2) measure Soil Stresses at different inflation pressures for the given wheel loads; and (3) measure subSoil Stresses and compare measured and simulated values. Measurements were made with the wheel loads 11, 15 and 33 kN at inflation pressures of 70, 100 and 150 kPa. TopSoil Stresses were measured at 10 cm depth with five Stress sensors installed in disturbed Soil, perpendicular to driving direction. Contact area was measured on a hard surface. SubSoil Stresses were measured at 30, 50 and 70 cm depth with sensors installed in undisturbed Soil. The mean ground contact pressure could be approximated by the tyre inflation pressure (only) when the recommended inflation pressure was used. The maximum Stress at 10 cm depth was considerably higher than the inflation pressure (39% on average) and also increased with increasing wheel load. While tyre inflation pressure had a large influence on Soil Stresses measured at 10 cm depth, it had very little influence in the subSoil (30 cm and deeper). In contrast, wheel load had a very large influence on subSoil Stresses. Measured and simulated values agreed reasonably well in terms of relative differences between treatments, but the effect of inflation pressure on subSoil Stresses was overestimated in the simulations. To reduce Soil Stresses exerted by tyres in agriculture, the results show the need to further study the distribution of Stresses under tyres. For calculation of subSoil Stresses, further validations of commonly used models for Stress propagation are needed.
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technical solutions to reduce the risk of subSoil compaction effects of dual wheels tandem wheels and tyre inflation pressure on Stress propagation in Soil
Soil & Tillage Research, 2004Co-Authors: Thomas Keller, Johan Arvidsson, Thomas Keller, Johan ArvidssonAbstract:Abstract The use of heavy machinery is increasing in agriculture, which induces increased risks of subSoil compaction. Hence, there is a need for technical solutions that reduce the compaction risk at high total machine loads. Three field experiments were performed in order to study the effects of dual wheels, tandem wheels and tyre inflation pressure on Stress propagation in Soil. Vertical Soil Stress was measured at three different depths by installing probes into the Soil horizontally from a dug pit. In one experiment, also the Stress distribution below the tyre was measured. Beneath the dual wheels, vertical Stresses at 0.15 and 0.3 m depth were lower between the two wheels than under the centre of each wheel, despite the gap between the wheels being small (0.1 m). At 0.5 m depth, vertical Stress beneath the wheels was the same as between the two wheels. The Stress interaction from the two wheels was weak, even in the subSoil. Accordingly, measured Stresses at 0.3, 0.5 and 0.7 m depth were highest under the centre of each axle centre line of tandem wheels, and much lower between the axles. For a wheel load of 86 kN, tyre inflation pressure significantly affected Stress at 0.3 m depth, but not at greater depths. Stress directly below the tyre, measured at 0.1 m depth, was unevenly distributed, both in driving direction and perpendicular to driving direction, and maximum Stress was considerably higher than tyre inflation pressure. Calculations of vertical Stress based on Boussinesq's equation for elastic materials agreed well with measurements. A parabolic or linear contact Stress distribution (Stress declines from the centre to the edge of the contact area) was a better approximation of the contact Stress than a uniform Stress distribution. The results demonstrate that Stress in the Soil at different depths is a function of the Stress on the surface and the contact area, which in turn are functions of wheel load, wheel arrangement, tyre inflation pressure, contact Stress distribution and Soil conditions. Soil Stress and Soil compaction are a function of neither axle load nor total vehicle load. This is of great importance for practical purposes. Reducing wheel load, e.g. by using dual or tandem wheels, also allows tyre inflation pressure to be reduced. This reduces the risk of subSoil compaction.