Geomechanics stability assessment of World War I military excavations at the Canadian National Vimy Memorial Site, France

The Canadian National Memorial Site, Vimy Ridge, France, commemorates the efforts and loss of life of Canadian troops in the First World War (WWI). The site comprises the monument, a Visitors Centre, the Grange Tunnels and restored trenches and several cemeteries. A substantial portion of the battlefield terrain remaining from WWI is preserved at this site, including trenches, shell holes and military mining craters. The ground surface is further disturbed by subsidence of the ground surface into underground excavations left from the war. A significant number of subsidence events have been recorded within the last decade. There is concern that ground surface subsidence could compromise the safety of visitors or workers at the site.