The failure of concrete retaining block (CRB) walls

[摘要] ENGLISH ABSTRACT: Concrete retaining block (CRB) walls have been identified by ECSA (the Engineering Council of South Africa) as a class of structures prone to failure. In South Africa, four major CRB wall failures occurred in Gauteng in one month alone. By identifying trends in the failures, engineers obtain a better understanding of how a CRB wall system works and how these retaining walls fail. This insight will assist engineers in designing more reliable retaining walls that will satisfy all the foreseen structural, environmental and construction demands.This study focuses on failed gravity and reinforced soil CRB walls in provinces throughout South Africa,including the Eastern Cape, Kwa-Zulu Natal and Gauteng. Through an extensive review of 18 case histories of failed CRB walls, common trends and aspects that typically cause problems with the walls are identified.The case histories were obtained from ECSA and private consulting engineering companies. The outcomes of the case histories focus on a description of the failure, identification of the problem and any designrelated issues. To further review the case histories effectively, the walls are classified and described according to specific criteria, and the basic failure mechanism(s) are identified. The information collected from this study is compared to the outcomes of previous studies. Furthermore, the outcomes of this study are described in such a manner as to be added to the database of the previous studies. The previous studies form part of the GSI (Geosynthetic Institute) database and focus on failed reinforced soil CRB walls on a global scale. Variations in the different studies are highlighted as the methods of classification, specifically regarding the backfill and the basic failure mechanism(s), are unique to each of the studies.An overall look into the previous and present studies allows the author to make recommendations toimprove the current shortcomings in the design and construction of CRB walls, as well as the manufacturing of CRB wall components. The major design and construction-related issues identified in both studies are very similar, with a few variations.The current study recognises 11 major design and construction-related issues pertaining to gravity andreinforced soil CRB walls. These issues specifically focus on the components of the system including thetype and placement/compaction of the backfill, an adequate drainage system and the placement thereof, construction drawings and specifications, performance monitoring, disruption of the system and the design itself.

[发布机构] Stellenbosch University