There are many regions where sub-surface voids, generally mineworkings or natural caverns (karstic rocks, including chalk), represent a potential hazard. Halcrow has extensive experience, in several countries, of the geotechnical issues associated with the investigation, assessment and treatment of both undermined and karstic ground. These projects include roads, railways, ports, buildings and tunnels.
The presence of cavities is usually established through a combination of techniques tailored to the site conditions. These include desk studies and historical research, the use of surface geophysical techniques, borehole investigations including probing, down-hole geophysics, packer testing and downhole cavity survey techniques. In some cases, human entry is possible. Halcrow has experience in the specification and use of all of these techniques.
Where infilling of the voids is the preferred solution, Halcrow has researched and developed the use of alternate materials compatible with site-specific environments. These seek to make maximum use of economic recycled materials, within the current Regulatory framework.
