Large Scale Testing of Drystone Retaining Structures

  • Chris Mundell

Student thesis: Doctoral ThesisPhD

Abstract

Drystone walls have been used extensively around the world as earth retaining structures wherever suitable stone is found. Commonly about 0.6m thick (irrespective of height), there are about 9000km of drystone retaining walls on the UK road network alone, mostly built in the 19th and early 20th centuries, with an estimated replacement value in excess of £1 billion[1]. Drystone wall design is traditionally empirical, based on local knowledge of what has worked in the past. Methods vary from region to region, driven by both custom and the nature of the materials available. Design is not necessarily optimised, and includes unknown margins of safety. There is a recognised need for guidance on the assessment and maintenance of dry stone retaining walls, as no suchdocumentscurrentlyexist. Thisthesisdocumentstheconstructionofaseriesoffull-scaletestsdesignedto provide sufficient information to validate current theoretical and numerical analysis techniques. The development of a unique test rig is detailed, in addition to the testing regime and results from a programme of five 2.5m high drystone retaining walls. The walls were subjected to localised surcharging and foundation movements, recreating the conditions that many in-situ walls are subject to. Movements such as toppling, bulging and sliding were observed, and recorded using a broad range of instrumentation. This has provided high quality, quantitative data relating to the factors which influence these mechanisms, and their affect on wall stability. Also documented are the associated laboratory tests which have been conducted to determine the mechanical properties of backfill and the walls themselves, as well as the manner in which they interact together. To assist in the analysis of these full-scale tests, a limit equilibrium program has been developed. This package allows the rapid generation of a wall of any size and constructed with any materials. The limit equilibrium program has then been used in conjunction with the data from the full-scale and laboratory tests to analyse observed drystone wall behaviour. These include the phenomena of toppling, bulging, bursting, sliding and individual block rotation. In each case, the underlying causes of such movements have been determined, and the critical parametersidentified.
Date of Award1 Aug 2009
LanguageEnglish
Awarding Institution
  • University of Bath
SupervisorPaul McCombie (Supervisor), Pete Walker (Supervisor) & Andrew Heath (Supervisor)

Keywords

  • masonry
  • retaining walls
  • drystone

Cite this

Large Scale Testing of Drystone Retaining Structures
Mundell, C. (Author). 1 Aug 2009

Student thesis: Doctoral ThesisPhD