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Demonstrating the value of case histories towards the improvement of knowledge and understanding of geotechnical problems using slope stability back-analysis.
Thesis (MEng)--Stellenbosch University, 2024.
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| Language: | en_ZA en_ZA |
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Stellenbosch : Stellenbosch University
2024
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| _version_ | 1867614115692806144 |
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| access_status_str | Open Access |
| author | Wright, Gary |
| author2 | MacRobert, Charles
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| author_browse | MacRobert, Charles
Wright, Gary |
| author_facet | MacRobert, Charles
Wright, Gary |
| author_sort | Wright, Gary |
| collection | Thesis |
| dc_rights_str_mv | Stellenbosch University |
| description | Thesis (MEng)--Stellenbosch University, 2024. |
| format | Thesis |
| id | oai:scholar.sun.ac.za:10019.1/130237 |
| institution | Stellenbosch University (South Africa) |
| language | en_ZA en_ZA |
| last_indexed | 2026-06-10T12:46:55.034Z |
| license_str | Other — see source repository |
| provenance_str_mv | Harvested via OAI-PMH from SUNScholar — Stellenbosch University Repository |
| publishDate | 2024 |
| publishDateRange | 2024 |
| publishDateSort | 2024 |
| publisher | Stellenbosch : Stellenbosch University |
| publisherStr | Stellenbosch : Stellenbosch University |
| record_format | dspace |
| source_str | SUNScholar — Stellenbosch University Repository |
| spelling | oai:scholar.sun.ac.za:10019.1/130237 Demonstrating the value of case histories towards the improvement of knowledge and understanding of geotechnical problems using slope stability back-analysis. Wright, Gary MacRobert, Charles Stellenbosch University. Faculty of Engineering. Dept. of Civil Engineering. Slopes (Soil mechanics) -- Stability Case histories Geotechnical engineering Landslides Thesis (MEng)--Stellenbosch University, 2024. ENGLISH ABSTRACT: This thesis sought to demonstrate the benefits of utilizing case histories as tool for the improvement of knowledge and understanding of geotechnical problems. For the purposes of demonstration, the problem of slope stability was considered. Four case histories and one original study concerning natural slope failures were selected and subjected to a stability back-analysis. Summaries and geotechnical models were created for each failure using information extracted from the respective case history, its cited sources, provided raw data, and Google Earth. The first failure considered a circular slip through colluvial material following heavy rain which damaged five properties in Camps Bay, South Africa. Study of the failure suggested that the slope was destabilised due to slope steepening during property development. Failure was then triggered due to water infiltration which resulted from a combination of heavy rainfall and an unmaintained stormwater inlet. An iterative back analysis was used to determine the shear strength parameters of the colluvial material at the time of failure. The results were validated by comparing the failure surface estimated by analysis software against the slip surface estimated through interpretation of surveyed movement monitoring data. The second failure considered a circular slip through alluvial material which damaged forty-five properties in Mossel Bay, South Africa. Back-analysis suggested the failure to be the result of an underlying weaker layer. This was supported by the results of a 2D and 3D analysis which predicted the critical failure surface, and many potential failure surfaces, to pass through the weaker layer. The third failure considered the shallow slip of a valley slope following heavy rain which damaged an athletic track in Shillong, India. Back-analysis suggested the failure to be the result of water infiltration introducing porewater pressures into the slope. A combined transient seepage and slope stability analysis using rainfall data was used to model the failure. Analysis results compared well to the actual failure. The fourth failure considered a circular slip through a riverbank comprised of clay in Drammen, Norway. A detailed 2D model was subjected to an Effective Stress analysis as well as a Total Stress analysis. Result of the Effective Stress analysis produced a Factor of Safety equal to approximately 1 while the Total Stress analysis produced a Factor of Safety below 1. Therefore, the Effective Stress analysis was determined to be the more accurate. Further analysis suggested that the slope was destabilized due to a low river level and triggered by the placing of fill material at the edge of the riverbank. The fifth failure considered debris flows following heavy rain which caused severe damage and loss of life in Chimanimani, Zimbabwe. The original study of the failure suggested that the slopes of Chimanimani were particularly sensitive to changes in ground water conditions. Results of a combined seepage and slope stability analysis suggested that the failures were the result of porewater pressures being introduced into the slope. The findings of the respective back-analyses were further considered for identification of common factors influencing failure. Slope destabilization and failure among the five studies was commonly attributed to changes in porewater pressure and those human or natural activities which change the geometry of the slope. The findings of this thesis suggest that these factors be given particular attention when performing a slope stability analysis. Furthermore, this thesis stresses the importance of performing a site investigation prior to development of natural slopes. Site investigations allow for the early detection of geotechnical problems which may then be addressed during the design phase. AFRIKAANSE OPSOMMING: Hierdie tesis het gepoog om die voordele te demonstreer van die gebruik van gevallestudies, as hulpmiddel, vir die verbetering van kennis en begrip van geotegniese probleme. Die probleem van hellingstabliliteit is oorweeg vir demonstrasie-doeleindes. Vier gevallestdies en een oorspronklike studie oor natuurlike hellingsversakings is gekies en aan 'n stabiliteit-teruganalise onderwerp. Opsommings en geotegniese modelle is vir elke mislukking geskep met behulp van inligting wat uit die onderskeie gevallestudies, die aangehaalde bronne, verskafde rou data en Google Earth onttrek is. Die eerste mislukking het ‘n sirkelvormige glip deur kolluviale materiaal na swaar reën wat vyf eiendomme in Kampsbaai, Suid-Afrika beskadig het oorweeg. Die studie van die mislukking het voorgestel dat die helling gedestabiliseer is as gevolg van die helling wat steiler word tydens eiendomsontwikkeling. Die mislukking is toe veroorsaak as gevolg van waterinfiltrasie wat voortgespruit het uit 'n kombinasie van swaar reënval en 'n ononderhoudende stormwaterinlaat. 'n Iteratiewe teruganalise was gebruik om die skuifsterkte parameters van die kolluviale materiaal te bepaal op die oomblik van mislukking. Die resultate is bekragtig deur die mislukkingsoppervlak wat deur ontledingsagteware beraam is, te vergelyk met die glipoppervlak wat beraam is deur die interpretasie van opgemete bewegingsmoniteringsdata. Die tweede mislukking het 'n sirkelvormige glip deur alluviale materiaal wat vyf-en-veertig eiendomme in Mosselbaai, Suid-Afrika beskadig het oorweeg. Die terug-analise het voorgestel dat die mislukking die gevolg was van 'n onderliggende swakker laag. Dit is bewys deur die resultate van 'n 2D- en 3D-analise wat voorspel het dat die kritieke foutoppervlakte, en baie potensiële mislukkingsoppervlaktes, deur die swakker laag beweeg. Die derde mislukking het die vlak glip van 'n valleihelling na swaar reën, wat 'n atletiekbaan in Shillong, Indië beskadig het, oorweeg. Die terug-analise het voorgestel dat die mislukking die gevolg was van waterinfiltrasie wat poriewaterdruk in die helling ingelaat het. 'n Gekombineerde kortstondige deursypeling en hellingstabiliteitsanalise deur gebruik te maak van reënvaldata is gebruik om die mislukking te modelleer. Ontledingsresultate het goed met die werklike mislukking vergelyk. Die vierde mislukking het 'n sirkelvormige glip deur 'n rivieroewer, wat uit klei bestaan het, in Drammen, Noorweë oorweeg. 'n Gedetailleerde 2D-model is aan 'n Effektiewe Stres-analise sowel as 'n Total Stres-analise onderwerp. Die resultaat van die Effektiewe Stres-analise het 'n Veiligheidsfaktor gelyk aan ongeveer 1 opgelewer, terwyl die Total Stres-analise 'n Veiligheidsfaktor onder 1 opgelewer het. Dit is daarom bepaal dat die Effektiewe Stres-analise die mees akkurate analise is. Verdere ontleding het voorgestel dat die helling gedestabiliseer is as gevolg van 'n lae riviervlak en veroorsaak is deur die plasing van vulmateriaal aan die rand van die rivieroewer. Die vyfde mislukking het puinvloei na swaar reën wat ernstige skade en lewensverlies in Chimanimani, Zimbabwe, veroorsaak het oorweeg. Die oorspronklike studie van die mislukking het voorgestel dat die hange van Chimanimani besonder sensitief was vir veranderinge in die grondwatertoestande. Resultate van 'n gekombineerde sypel- en hellingstabiliteitsanalise het voorgestel dat die mislukkings die gevolg was van poriewaterdruk wat in die helling ingebring is. Die bevindinge van die onderskeie terugontledings is verder oorweeg vir die identifisering van algemene faktore wat mislukking beïnvloed. Hellingdestabilisering en mislukking onder die vyf studies is algemeen toegeskryf aan veranderinge in poriewaterdruk en daardie menslike of natuurlike aktiwiteite wat die geometrie van die helling verander. Die bevindinge van hierdie tesis dui daarop aan dat daar veral aan hierdie faktore aandag gegee moet word wanneer 'n hellingstabiliteitsanalise uitgevoer word. Verder beklemtoon hierdie tesis die belangrikheid van 'n terreinondersoek voor die ontwikkeling van natuurlike hellings. Terreinondersoeke maak voorsiening vir die vroeë opsporing van geotegniese probleme wat dan tydens die ontwerpfase aangespreek kan word. Masters 2024-02-22T14:01:20Z 2024-04-26T10:17:52Z 2024-02-22T14:01:20Z 2024-04-26T10:17:52Z 2024-03 Thesis https://scholar.sun.ac.za/handle/10019.1/130237 en_ZA en_ZA Stellenbosch University xiii, 58 pages : illustrations application/pdf Stellenbosch : Stellenbosch University |
| spellingShingle | Slopes (Soil mechanics) -- Stability Case histories Geotechnical engineering Landslides Wright, Gary Demonstrating the value of case histories towards the improvement of knowledge and understanding of geotechnical problems using slope stability back-analysis. |
| title | Demonstrating the value of case histories towards the improvement of knowledge and understanding of geotechnical problems using slope stability back-analysis. |
| title_full | Demonstrating the value of case histories towards the improvement of knowledge and understanding of geotechnical problems using slope stability back-analysis. |
| title_fullStr | Demonstrating the value of case histories towards the improvement of knowledge and understanding of geotechnical problems using slope stability back-analysis. |
| title_full_unstemmed | Demonstrating the value of case histories towards the improvement of knowledge and understanding of geotechnical problems using slope stability back-analysis. |
| title_short | Demonstrating the value of case histories towards the improvement of knowledge and understanding of geotechnical problems using slope stability back-analysis. |
| title_sort | demonstrating the value of case histories towards the improvement of knowledge and understanding of geotechnical problems using slope stability back analysis |
| topic | Slopes (Soil mechanics) -- Stability Case histories Geotechnical engineering Landslides |
| url | https://scholar.sun.ac.za/handle/10019.1/130237 |
| work_keys_str_mv | AT wrightgary demonstratingthevalueofcasehistoriestowardstheimprovementofknowledgeandunderstandingofgeotechnicalproblemsusingslopestabilitybackanalysis |