Hagos, Ataklti (2017) Assessment of Causes for Partial Settlement of Gidabo Dam, Southern Ethiopia. Masters thesis, Addis Ababa University.
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Abstract
The present study was carried out at Gidabo Dam, which is proposed on Gidabo River in Oromia Regional State, about 375 km from Addis Ababa, the capital city of Ethiopia. Gidabo Dam has faced settlement at the conduit outlet foundation during the construction time which was measured to be about 0.4 m. The main objectives of this study were to assess the possible causes of partial settlement and to estimate the amount of potential future settlement of the dam. The general methodology followed for the present study was based on thorough literature review, field investigations and data collection, analysis and evaluation of various soil parameters of settlement. For the present study immediate and primary settlement analysis was carried out. Elastic theory for cohesive soils, Janbu’s approach and one dimensional settlement analysis were applied to estimate the settlement amount of the upper part of backfill foundation unit and compressible silty clay layer of the dam foundation. For the granular soil foundation at the bottom immediate settlement was estimated from in-situ standard penetration test (SPT) results. The present study results showed excessive settlement. The estimated settlement is more than the expected settlement as anticipated in the design of the dam. The differential settlement is also expected at the contact of the backfill material, at outlet conduit and in between the intake tower and the outlet conduit. As investigated in the present study, the primary causes of the settlement are related to unsuitable backfill material comprising alluvium backfill and clay cutoff, compressible silty clay layer (organic) below the excavation and due to inappropriate excavation method (dewatering process) followed during the construction stage. Besides, granular type of soil in the foundation has also contributed for the settlement of the dam in general, and of conduit section in particular. The study also showed that this settlement also continue in future. Therefore, it is strongly recommended to adopt appropriate measures, as suggested through the present study, so that possible safety and stability of the dam can be ensured during the performance stage.
| Item Type: | Thesis (Masters) |
|---|---|
| Uncontrolled Keywords: | Gidabo dam; Settlement analysis; Janbu Settlement analysis; Consolidation |
| Subjects: | Q Science > Q Science (General) Q Science > QE Geology |
| Divisions: | Africana |
| Depositing User: | Selom Ghislain |
| Date Deposited: | 06 Sep 2018 13:48 |
| Last Modified: | 06 Sep 2018 13:48 |
| URI: | http://thesisbank.jhia.ac.ke/id/eprint/4968 |
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