How a diver saved Winchester Cathedral, UK: and today's solution?

Abstract

In 1905 there were concerns about the dangerous state of Britain's Winchester Cathedral, some walls having subsided significantly while others were leaning out dangerously or had cracks and voids. A trial hole confirmed a high water table with compressible peat overlying a gravel bed. Francis Fox was consulted and recommended grouting the cavities, installing tie-rods and the temporary shoring up of some walls before underpinning them down to the gravel bed. Pits dug to start the underpinning operation rapidly filled with black peaty water thereby reducing visibility to almost nil. Conventional pumping being considered too dangerous, a diver excavated and then bottom-sealed pits dug under the walls, thus enabling the remainder of the underpinning work to be completed by others. Eventually the work was extended to virtually all the cathedral's walls, the diver remaining on site for 5 years, carrying out most of his work underwater in a diving suit and by feel and touch. Studies undertaken in 2006–2007 confirmed that the structure was stable but suggested that, before deciding to underpin the walls, Fox might have instituted more investigations. It was also thought that, if foundation strengthening was considered necessary now, it would probably comprise some form of micropiling.