CJFP Jones, BSc, MSc, Pho, CEng, MICE. This paper was first published in GE’s September 1979 edition.
The Building Research Establishment, together with the Department of Transport recently commissioned a review of the foundation and sub-structure methods used in the design. of small and medium span bridges. The study, which was based upon a series of exhaustive interviews with practising engineers, gives a comprehensive view of the design of conventional earth retaining structures (BRE, 1977).
In an opening commentary it is argued that our retaining wall design is based upon experience of structures going back 150 years. Indeed, most modern earth retaining structures are based upon derivations of the classical theories of Coulomb (1773) and Rankine (1857) and although field evidence shows that the assumptions made with these theories are demonstratively incorrect, there are few retaining walI failures associated with modern construction.
At the same time, application of our current design rules to those walls which are 100/150 years old suggest that they should not stand up and, indeed, there is growing evidence that many are reaching the end of their life. Further inspection shows that the Victorians hed very different ideas and used different techniques when buiIding walls and it is perhaps relevant to question whether we are basing our current practice on 150 years worth of experience or whether modern methods are such as to make any comparison with the past impossible.