Improvement of dam filter criterion for cohesionless base soils | |
| Author | Kwang, Ah Tsai |
| Call Number | AIT Thesis no.GT-89-19 |
| Subject(s) | Filters and filtration Dams |
| Note | A thesis submitted in partial fulfillment of the requirements for the degree of Master of Engineering, School of Engineering and Technology |
| Publisher | Asian Institute of Technology |
| Abstract | Filters had been used in dams and other· earth structures for more than half a decade and Terzaghl 's criterion is used widely for a long time. However, it is found that this criterion is unconservative under certain soil conditions especially for soils with a widely graded coarse portion. Some laboratory tests using both screen to act as a filter as well as actual soil filter were run to determine the behaviour of base soils with a widely graded coarse portion as well as on gap-graded soils. Tests on varying the gradation of the base soil at the coarser portion revealed that there is generally an increase in instability if the gradation of the coarse portion becomes wider. From test results it was suggested to improve Terzaghi's piping criterion by specifying that the mass fraction within DB85 and 4 times DB85 to be more than 5 percent to ensure that the condition of stability is satisfied. Tests on gap-graded soils reveal that as the gap range increases, the amount of intermediate sizes needed to resume stability increases correspondingly. For widely graded natural soils, they are analogous to widely gap-graded soils with a little intermediate size, and thus there should also be a minimum amount of intermediate sizes which should be present to sustain stability of the base soil. From case studies of some widely graded dam core materials, it was suggested that the mass fraction within any diameter d and 4 times d of the material should be more than 10 percent to ensure there is no internal stability. |
| Year | 1990 |
| Type | Thesis |
| School | School of Engineering and Technology (SET) |
| Department | Other Field of Studies (No Department) |
| Academic Program/FoS | Geotechnical and Transportation Engineering (GT) |
| Chairperson(s) | Honjo, Yusuke |
| Examination Committee(s) | Prinya Nutalaya ;Indraratna, Buddhima |
| Scholarship Donor(s) | DAAD, Federal Republic of Germany |
| Degree | Thesis (M.Eng.) - Asian Institute of Technology, 1990 |