| Author | Pathak, Bikash Kumar |
| Call Number | AIT Thesis no.AE-91-10 |
| Subject(s) | Tillage
|
| Note | A thesis submitted in partial fulfilment of the requirements
for the degree of Master of Engineering |
| Publisher | Asian Institute of Technology |
| Abstract | The soil failure patterns and corresponding soil reactions
under the action of flat vertical tools operating at quasi-static
conditions in dry compact sand were studied. The soil failure
was found to be by progressive shear, starting horizontally from
the tool tip up to a certain distance and then progressing upward
towards horizontal soil surface. The shear angle was found to be
27° ± 2°, which was very close to the theoretical angle (π/4-Φ/2 )
of 26.5°, for all the tools studied. With increase in tool depth,
even at the same aspect ratio, the additional shearing within
already failed zones of soil became more and more prominent. At
depths of 5 and 7.5 cm, the failure patterns remained almost the
same with a change in aspect ratio, whereas at higher depths of
10 and 12.5 cm the failure patterns were found to change with
tool aspect ratio. An additional shearing within already failed
zones was also progressive in nature starting from top of the
tool at an angle of 40° to 50° which was less than the theoretical
angle (90°-Φ) of 53°. The vertical and horizontal soil reactions
were cyclic in nature and were in phase for all the tools
under study. Wavelength and amplitude of horizontal soil reaction
was found to increase with tool aspect ratio and depth.
The stabilized surcharge took a distinct shape. The front
portion was very close to quarter of an ellipsoid and the rear
portion to a triangular wedge. Based on this shape, a model was
developed to predict the stabilized surcharge weight. Predicted
values were very close to the observed data at lower tool depths.
With an increase in tool aspect ratio and depth, the observed
data were found to be lower than the predicted values possibly
due to the reason that the surcharge was not fully stabilized for
bigger tools. The observed data and predicted values followed the
same trend. |
| Year | 1991 |
| Type | Thesis |
| School | School of Environment, Resources, and Development (SERD) |
| Department | Department of Food, Agriculture and Natural Resources (Former title: Department of Food Agriculture, and BioResources (DFAB)) |
| Academic Program/FoS | Agricultural and Food Engineering (AE) |
| Chairperson(s) | Salokhe, Vilas M.; |
| Examination Committee(s) | Gee-Clough, D.;Gupta, C.P.;Maohua, Wang; |
| Scholarship Donor(s) | Royal Netherlands Government; |
| Degree | Thesis (M.Eng.) - Asian Institute of Technology, 1991 |