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| dc.contributor.author | AMELMAL, GELAYE BERIE | |
| dc.date.accessioned | 2022-03-01T07:21:15Z | |
| dc.date.available | 2022-03-01T07:21:15Z | |
| dc.date.issued | 2021-10 | |
| dc.identifier.uri | http://ir.bdu.edu.et/handle/123456789/13085 | |
| dc.description.abstract | Particle shape plays an important role in the engineering behavior of the soil in terms of its permeability, packing density, dilatancy and shear strength. Dilatancy is the ability of granular soil to change in volume under shearing stresses. It influences granular material behavior, ranging from shear strength to stress-strain behavior. In this study the effect of particle shape on dilatancy of granular soil in some locations of Ethiopia was studied. A microscope was used to capture grain images with sufficient quality to observe the soil grain shape profile. After obtaining digital images of individual grains, it was analyzed with a digital image processing software, ImageJ. Roundness, circularity and inverse of the aspect ratio were determined for Abay Sand, Addis Zemen Sand and Lalibela Sand from field sites in Ethiopia. The effects of particle form (i.e., roundness, inverse aspect ratio, and circularity), specimen density, and normal stress on the shear strength parameters of dry sand specimens were studied. Three types of uniform sand (with different grain shape profiles) with grain sizes in between U.S. Sieve No. 40 and U.S. Sieve No. 50 were tested at 53.1 kPa, 106.2 kPa, 212.4 kPa and 371.7 kPa normal stress under the direct shear test. The influence of particle shape on dilatancy, peak state and critical state friction angles were examined. The experimental results indicates that the rounded grains, Abay Sand, allow for expansion within the granular mass at high normal stress, whereas the angular grains configure themselves such that volume expansion is suppressed at high normal stress. A stepwise regression analysis was performed with the help of JMP ® Pro14 statistical software and a statistical model capable of predicting the dilatancy angle by providing grain shape parameters, relative density and normal stresses as input parameters were developed. The model predicts with a coefficient of determination 97.4% and root mean square error of 0.149. A cross-validation technique was utilized to validate the proposed dilatancy prediction model. The prediction model was built using 27 data from the observations, and the remaining nine data were utilized to validate the suggested model. The predictive model shows that grain shape parameters influence dilatancy angle with acceptable fit statistics and internal validity. It is recommended that the model can predict the dilatancy angle of granular soil without the need to perform a set of experiments. And it will be a good input for geotechnical engineers to reduce uncertainties related to shear strength. Keywords: Grain shape; Microscope; ImageJ; Shear strength; Dilatancy; Predictive Model; JMP ® Pro 14; Model validation | en_US |
| dc.language.iso | en_US | en_US |
| dc.subject | CIVIL AND WATER RESOURCE ENGINEERING | en_US |
| dc.title | EFFECTS OF PARTICLE SHAPE ON DILATANCY CHARACTERSTICS OF GRANULAR GEOMATERIALS UNDER LOAD | en_US |
| dc.type | Thesis | en_US |
