Date post: | 16-Jan-2016 |
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Breaking up the compacted layer to loosen the soil
Requiring high draft power and resulting inhigh soil disturbance
Discrete element modeling (DEM) to simulate the subsoiling process
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Source: www.fao.org
Discrete element method (DEM) To study the behavior of granular material Repeated application of Newton’s second law and a
force-displacement law More detailed study of micro-dynamics of material
Particle Flow Code in 3 Dimension (PFC3D) A commercial DEM software package Modeling problems in solid mechanics and granular flow
3Source: Itasca (2003)
To develop a PFC3D model to predict soil cutting forces and soil loosening
To calibrate model parameters of soil
To validate the model with field measurements
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6Source: Itasca (2003)
Depicted as a cylinder of cementatious material
Envisioned as a set of elastic springs
Transmitting both force and moments
Bond breaking
Young’s modulus of the bond unknown
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Soil particle› Range of particle size› Particle-particle friction
coefficient› Young’s modulus › Ratio of normal and shear
stiffness › Bulk density
Soil box› Length, width, and height
Parallel bond between soil particles
› Radius of the bond› Bond normal and shear strength› Young’s modulus (To be calibrated)› Bond stiffness ratio
Subsoiler› Soil-subsoiler friction coefficient› Subsoiler stiffness› Subsoiler travel speed› Tillage depth
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Field conditions: Oakville, Manitoba, Canada Tillage depth & speed: 300 mm, 3 km/h Clay soil
Data collection Soil cutting pressure Soil dry bulk density Soil total porosity
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10Sensing circle: 4.8 mm radiusSensing area: 71 mm2
FlexiForce sensors were used to measure the soil pressure on the subsoiler and to calibrate the model
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Side view of the field operationBack view of the model
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Successful simulation of soil behaviour with PFC3D in terms of soil-subsoiler interaction force measurements and soil porosity changes
Young’s modulus of 105 Pa for the soil bond giving the best match between the measured and predicted soil pressures
Appropriate method of simulating soil aggregates, not individual soil particles as “particles” in PFC3D when simulating agricultural clay soils
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Simulating soil cutting forces and soil loosening resulting from the ripper at different tillage depths
Validating the simulation results against the field measurements and the universal earthmoving equation
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