Civil engineering often needs detailed information about the subsurface before starting construction of dams, bridges, roads, airports, buildings, tunnels, and so on. In the past, site investigation relied heavily on drilling, but though drilling can provide essential information it can miss important features between boreholes, and it does not give information about hazards such as earthquakes. A better strategy is first to carry out a combined geological and geophysical survey, and then concentrate drilling where the survey shows it will be most useful. For successful results, geophysicists and geologists need to be clear what information the engineer needs, while the engineer needs to understand what kinds of information the geophysicist and geologist can offer, and their limitations.
Applications where geophysics can be of use to civil engineers include mapping earthquake probability and severity; measuring the depth of unconsolidated cover or weathering, or the extent of infilling; detecting fracture zones; finding pipes and buried objects; locating voids, caves, and old mine workings; and investigating contaminated ground. Some of these have already been considered briefly, such as earth quakes (Chapter 5) and contaminated ground (Section 26.7). This chapter considers only the investigation of cavities and voids, which offers straightforward applications of geophysics.
Introduction
Unrecognised cavities beneath a site could lead to settling or collapse of the structure, or, in the case of dams and settling ponds, allow the contents to escape. Cavities may be natural or artificial.
Review the options below to login to check your access.
Log in with your Cambridge Aspire website account to check access.
If you believe you should have access to this content, please contact your institutional librarian or consult our FAQ page for further information about accessing our content.