The influential CIRIA C580 Report, which provides guidance on the design of embedded retaining walls, is currently being updated.
This project supports the update by means of a thorough review of existing design codes and studies, comparing different design approaches, assumptions and recommendations for applying factors of safety. The purpose of this research is to produce a comprehensive commentary, with worked examples, illustrating the issues facing the designer of an embedded retaining wall.
The existing EC7 guide is a continuous source of confusion among practicing UK engineers. The CIRIA C580 update aims to produce a clear, efficient guide for the economic design of embedded retaining walls. The recommendations published will encourage the industry to analyse these geotechnical structures by considering structural and geotechnical failures together.
Four geometries, assessing both effective and total stress conditions for a simple cantilever and a singly propped embedded retaining wall, were analysed. Three methods of analysis were used: limit equilibrium, pseudo-finite element, and finite element. These were investigated through three different computer software packages: FREW, WALLAP and PLAXIS. The problems were solved using design approaches recommended by the current C580 report, EC7 and the proposed update.
For the cantilever wall, a similar range of results were expected, irrespective of the method of analysis used, since there is little stress redistribution. However, stresses are redistributed when the wall is propped, resulting in overestimated wall responses and underestimated prop loads in the basic limit equilibrium analyses.
The results mainly agreed with these expectations. Possible causes of the discrepancies were identified, including modelling limitations and approximations used by the software. The results supported the design recommendations to be included in the CIRIA C580 update. However, one method of analysis was not identified as consistently better than another. Therefore, the designer must chose a method appropriate to the situation being modelled, and ensure efficiency of design and economy are achieved.
This project supports the update by means of a thorough review of existing design codes and studies, comparing different design approaches, assumptions and recommendations for applying factors of safety. The purpose of this research is to produce a comprehensive commentary, with worked examples, illustrating the issues facing the designer of an embedded retaining wall.
The existing EC7 guide is a continuous source of confusion among practicing UK engineers. The CIRIA C580 update aims to produce a clear, efficient guide for the economic design of embedded retaining walls. The recommendations published will encourage the industry to analyse these geotechnical structures by considering structural and geotechnical failures together.
Four geometries, assessing both effective and total stress conditions for a simple cantilever and a singly propped embedded retaining wall, were analysed. Three methods of analysis were used: limit equilibrium, pseudo-finite element, and finite element. These were investigated through three different computer software packages: FREW, WALLAP and PLAXIS. The problems were solved using design approaches recommended by the current C580 report, EC7 and the proposed update.
For the cantilever wall, a similar range of results were expected, irrespective of the method of analysis used, since there is little stress redistribution. However, stresses are redistributed when the wall is propped, resulting in overestimated wall responses and underestimated prop loads in the basic limit equilibrium analyses.
The results mainly agreed with these expectations. Possible causes of the discrepancies were identified, including modelling limitations and approximations used by the software. The results supported the design recommendations to be included in the CIRIA C580 update. However, one method of analysis was not identified as consistently better than another. Therefore, the designer must chose a method appropriate to the situation being modelled, and ensure efficiency of design and economy are achieved.
