Civil Engineering November 2022 | Vol 30 No 10

Civil Engineering November 2022 47 MSE wall system. This option had the advantage that many of the existing wall components could be reused, further reducing the environmental impact while considering the affordability of materials and time constraints during construction. Additionally, modifications to the existing design were required to comply with applicable standards. In this regard, a re- ticulated micropiling system was designed to account for the global stability issues associated with groundwater changes. The second option entailed removing the existing wall and realigning the road by cutting into the top slope above the road. Finally, to retain the cut, a soil nail wall was proposed. The second option would provide a more robust solution, as it avoided the application of surcharge to the crest of the very steep slope, hence it was selected as the preferred solution. In addition, it would be a simpler option that would not require the design of complicated retaining systems. As a result, system efficiency would be improved, global stability issues would be mitigated, and the problems associated with fill would not arise due to the removal of the MSE system. Apart from shifting the road away from the top of the slope, guardrails were also proposed to provide a safety barrier and prevent motorists from driving down the steep drop-off at Wall No.2. CONCLUSION SMEC has completed the first two phases of the project, which include an investigation into the cause of failure of the retaining wall and an option analysis that considered various remedial work options and proposed a preferred solution to proceed to detailed design. The study shows that even though it may be difficult to determine specific causes for the failure of MSE walls, the observational method can serve as a useful tool for carrying out these investigations. This study emphasises the importance of conducting an appropriate geotechnical investigation and conducting an extensive numerical investigation using all available information to reach a consensus regarding the geomechanical properties of the mate- rial. Once the geomechanical properties of the slope had been established, an investigation was conducted into the slope’s sensitivity to changes in boundary conditions as well as simulating the failure of the slope using actual site observations. Although there were a number of chal- lenges, the investigation was completed within budget and on time. As part of the project, the community was actively involved, and while it was not a labour- intensive project, all efforts were made to meet the needs and expectations of the community. In addition, SMEC provided learning and upskilling activities that benefited both its clients and society in general, as well as supporting the applica- tion for professional registration with ECSA by an engineer employed by the KZN Department of Transport. SMEC is awaiting approval of the preferred solution by the KZN Department of Transport before detailed design com- mences. The preferred solution would re- quire additional budget for the re-alignment and pavement design which will require Stage-Gate approvals as per the KZN Department of Transport mandate.  Years of Making Life Simpler It takes clients with vision and passionate teams to engineer infrastructure that improves the quality of life in our communities. Transportation \ Water & Sanitation \ Structures \ Management Services \ Infrastructure Planning \ Strategic Projects Thank you to all who have partnered with Mariswe in South Africa and abroad over the past 50 years. We are proud of what we have created and excited to add more value together in the future.