| Autor: |
Lubomír Petrula, Jaromír Říha, Mario Hala |
| Rok vydání: |
2018 |
| Předmět: |
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| Zdroj: |
Lecture Notes in Civil Engineering ISBN: 9783319994222 |
| DOI: |
10.1007/978-3-319-99423-9_8 |
| Popis: |
One of the local defects in soils due to seepage is heave. This may occur at the downstream toe of hydraulic structures in the case of upward external seepage where particles of uniform soils are subject to uplift and also upward seepage forces. The phenomena starts with gradual liquefaction of soil grains accompanied by gradual loss of shear strength followed by boiling, heave and possible backward erosion and overall collapse of the structure. The problem of heave has been addressed by numerous authors who have published relationships based on the balance of forces and also on results of laboratory experiments. In this paper the results of extensive systematic experimental research carried on glass beads subjected to upward seepage in the vertical Darcy apparatus are presented. Three glass beads’ diameters 0.2 mm, 0.5 mm and 1.0 mm with uniformity coefficient CU from 1.1 to 1.3 and different porosity n from 0.36 to 0.44 were tested. To enable statistical evaluation of the uncertainty in critical hydraulic gradient 177 individual tests have been performed. The results of measurements were analysed and compared with relationships proposed by various authors. The best agreement was provided by the well-known Terzaghi formula relating the critical gradient to the specific mass of grains and soil porosity. Based on the experimental data the uncertainty in the use of Terzaghi formula was expressed via reliability coefficients recommended for use in technical practice. |
| Databáze: |
OpenAIRE |
| Externí odkaz: |
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