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Structural analysis and repair strategy for an ASR damaged dam structure
Thesis (MEng)--Stellenbosch University, 2021.
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| Format: | Thesis |
| Language: | en_ZA |
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Stellenbosch : Stellenbosch University
2021
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| _version_ | 1867613948414525440 |
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| access_status_str | Open Access |
| author | De Jongh, Lana |
| author2 | Van Zijl, P. A. G. |
| author_browse | De Jongh, Lana Van Zijl, P. A. G. |
| author_facet | Van Zijl, P. A. G. De Jongh, Lana |
| author_sort | De Jongh, Lana |
| collection | Thesis |
| dc_rights_str_mv | Stellenbosch University |
| description | Thesis (MEng)--Stellenbosch University, 2021. |
| format | Thesis |
| id | oai:scholar.sun.ac.za:10019.1/123877 |
| institution | Stellenbosch University (South Africa) |
| language | en_ZA |
| last_indexed | 2026-06-10T12:44:15.221Z |
| license_str | Other — see source repository |
| provenance_str_mv | Harvested via OAI-PMH from SUNScholar — Stellenbosch University Repository |
| publishDate | 2021 |
| publishDateRange | 2021 |
| publishDateSort | 2021 |
| publisher | Stellenbosch : Stellenbosch University |
| publisherStr | Stellenbosch : Stellenbosch University |
| record_format | dspace |
| source_str | SUNScholar — Stellenbosch University Repository |
| spelling | oai:scholar.sun.ac.za:10019.1/123877 Structural analysis and repair strategy for an ASR damaged dam structure De Jongh, Lana Van Zijl, P. A. G. Stellenbosch University. Faculty of Engineering. Dept. of Civil Engineering. Repair strategy Dam structure Kleinplaas dam UCTD Structural analysis (Engineering) Dams -- Maintenance and repair Concrete dams ASR (Water storage) Thesis (MEng)--Stellenbosch University, 2021. ENGLISH ABSTRACT: The Kleinplaas dam is a concrete gravity dam situated in the Jonkershoek area of Stellenbosch, Western Cape, South Africa. The dam wall has experienced approximately 35 years of ASR deterioration and by monitoring the displacements of the cracks and crest of the dam wall, it was determined that the reaction has likely stopped. This research continued on the work done by Pourbehi (2018) who developed a numerical model (SU-ASR FE subroutine for Abaqus) to determine the ASR extent in the concrete and the level of mechanical damage it has caused over the life span of the Kleinplaas dam. The goal of this research was to set up a proposed repair strategy to improve the structural stability of the ASR affected dam wall to prevent instability in a seismic event. Different repair strategies previously implemented on structures suffering from ASR were researched and tested on the Kleinplaas dam wall structure using Abaqus commercial finite element software and the numerical model developed by Pourbehi (2018). The repair strategies were then computationally tested under seismic conditions as well to confirm whether the repaired structure will be stable in a seismic event. The best repair strategy was chosen based on the results of the study. To determine the ASR extent in the Kleinplaas dam, a coupled thermal-stress analysis using the SU-ASR FE subroutine was performed and this was followed by the crack formation numerical modelling to assess the current condition of the dam wall. A subsequent seismic damage analysis of the Kleinplaas dam wall was performed with an expected earthquake for the region to determine what further damage could be caused to the dam wall. The results supported the conclusion that the ASR extent in the Kleinplaas dam wall has reached 100% and the stiffness of the dam possibly decreased to 25.6%. The computed seismic results showed possible severe damage at the base of the dam wall. The literature on the practice of stabilising and strengthening ASR affected hydraulic structures showed that a post-tensioned anchor could be a good stabilising method for a concrete gravity dam and this method was researched and tested with the Kleinplaas dam numerical model. The possibility of refilling the localised cracks with epoxy was considered and analysed in the seismic damage analysis. The results were compared to the previous model with no epoxy fill and the tensile stresses in the dam wall found to be lower when epoxy fill was applied to the cracks. The diagonal post-tensioned anchor repair solution was investigated using the Kleinplaas dam numerical model. The anchor was added to the model at 28° vertical inclination, from the dam crest, through the dam between the gallery and downstream face, and anchored by an approximately 5 m long part embedded and grouted in the founding rock. Anchor sizes of 15, 20 and 25 number of strands as options for three different tensioning load combinations (70%, 60% and 55% of the breaking load) were analysed. After further seismic damage analysis of these options, the recommended solution was to install a 25 strand post-tensioned anchor which will be tensioned at 70% of the breaking load per metre in the worst affected part of the dam. AFRIKAANSE OPSOMMING: Die Kleinplaas dam is 'n betongravitasiedam in die Jonkershoek omgewing van Stellenbosch, Wes-Kaap, Suid-Afrika. Die damwal het ongeveer 35 jaar van ASR beleef en deur die verplasings van die skeure en kruin van die damwal te monitor, was vasgestel dat die reaksie waarskynlik gestop het. Hierdie navorsing sit Pourbehi (2018) se werk voort, wat 'n numeriese model (SU-ASR FE subroetine vir Abaqus) ontwikkel het om die ASR-omvang van die beton en die vlak van meganiese skade wat dit gedurende sy lewensduur aangerig het, te bepaal vir die Kleinplaas dam. Die doel van hierdie navorsing was om 'n herstelstrategie voor te stel om die strukturele stabiliteit van die ASR-geaffekteerde damwal te verbeter om onstabiliteit te voorkom tydens 'n aardbewing. Verskillende herstelstrategieë wat voorheen geïmplementeer was op strukture wat aan ASR ly, was ondersoek en numeries getoets op die Kleinplaas damwalstruktuur met behulp van Abaqus kommersiële eindige element sagteware en die numeriese model wat voorheen deur Pourbehi (2018) ontwikkel is. Die herstelstrategieë was daarna ook onder seismiese toestande getoets om te sien of die herstelde struktuur stabiel sou wees tydens 'n seismiese gebeurtenis. Aan die einde van die studie was die beste herstelstrategie gekies, op grond van die berekende resultate. Om die ASR-omvang in die Kleinplaas dam te bepaal, was 'n gekoppelde termo-meganiese analise met behulp van die SU-ASR FE-subroetine uitgevoer, en dit was gevolg deur die numeriese modellering van die kraakvorming om die huidige toestand van die damwal te bepaal. 'n Daaropvolgende seismiese skade analise van die Kleinplaas damwal was uitgevoer met 'n aardbewing wat in die streek kon voorkom, om vas te stel watter verdere skade aan die damwal aangerig kon word. Uit die resultate was tot die gevolgtrekking gekom dat die ASR- omvang in die Kleinplaas damwal 100% bereik het en dat die styfheid van die dam moontlik tot 20 GPa verminder het. Die seismiese resultate het moontlike ernstige skade aan die voet van die damwal getoon. Die literatuur oor die praktyk om hidrouliese strukture wat deur ASR geraak word, te stabiliseer en te versterk, het getoon dat 'n nagespande anker 'n goeie stabiliseringsmetode vir 'n betongravitasiedam kan wees, en hierdie metode was ondersoek en getoets met die Kleinplaas dam numeriese model. Die moontlikheid om die gelokaliseerde krake weer met epoksie te hervul, was oorweeg en ontleed met behulp van die seismiese skade analise. Die resultate was vergelyk met die vorige model sonder epoksievulsel en die trekspanning in die damwal blyk laer te wees vir die geval van epoksie herstel van die krake. Die diagonale nagespande ankerhersteloplossing was ondersoek met behulp van die Kleinplaas dam numeriese model. Die anker was in die model teen 'n vertikale helling van 28° bygevoeg, vanaf die kruin van die dam, deur die wal tussen die gallery en stroom-af rand, en met sowat 5 m in die fondering rots veranker. Ankergroottes van 15, 20 en 25 aantal stringe as opsies vir drie verskillende spanningslaskombinasies (70%, 60% en 55% van die breuklas) was ontleed. Na 'n verdere seismiese skade analise van hierdie opsies, was die aanbevole oplossing om 'n 25-string nagespande anker te installeer teen 70% van die breuklas nagespan, per meter van die damwal in die ergste geaffekteerde deel van die dam. Masters 2021-12-01T09:27:18Z 2021-12-22T14:26:36Z 2021-12-01T09:27:18Z 2021-12-22T14:26:36Z 2021-12 Thesis http://hdl.handle.net/10019.1/123877 en_ZA Stellenbosch University 136 pages application/pdf Stellenbosch : Stellenbosch University |
| spellingShingle | Repair strategy Dam structure Kleinplaas dam UCTD Structural analysis (Engineering) Dams -- Maintenance and repair Concrete dams ASR (Water storage) De Jongh, Lana Structural analysis and repair strategy for an ASR damaged dam structure |
| title | Structural analysis and repair strategy for an ASR damaged dam structure |
| title_full | Structural analysis and repair strategy for an ASR damaged dam structure |
| title_fullStr | Structural analysis and repair strategy for an ASR damaged dam structure |
| title_full_unstemmed | Structural analysis and repair strategy for an ASR damaged dam structure |
| title_short | Structural analysis and repair strategy for an ASR damaged dam structure |
| title_sort | structural analysis and repair strategy for an asr damaged dam structure |
| topic | Repair strategy Dam structure Kleinplaas dam UCTD Structural analysis (Engineering) Dams -- Maintenance and repair Concrete dams ASR (Water storage) |
| url | http://hdl.handle.net/10019.1/123877 |
| work_keys_str_mv | AT dejonghlana structuralanalysisandrepairstrategyforanasrdamageddamstructure |