Earthscan Geoscience utilizes a range of geophysical survey methods with applications in geotechnical services investigations such as depth to bedrock, cavity, fault or utility location and mineral reserve assessment.
Subsurface ground conditions are often only spot sampled by drilling and test pits. While this can give you detailed information at that point, it does not tell you about variations in the properties of the ground between points. Modern geophysical survey methods, whether performed in terrestrial or in marine environments, allows a rapid assessment of site conditions using non-invasive, remote-sensing techniques. Data provided by geophysical surveys can improve the success of traditional sampling techniques by allowing specific target areas to be investigated. Improved interpretation between boreholes, using geophysical data, frequently leads to limiting the number of boreholes needed to complete the characterization of the site, thus providing economic benefits to a greater understanding of the site.
Examples of applications and Geotechnical Services include:
- Ground characterization – The determination of lateral variation, bedrock depth, velocity structure, ripability, saline or freshwater interfaces, sedimentology, faults, and mineral reserve assessment.
- Cavity mapping – The detection and delineation of cavities and voids such as those in mine workings or karst systems.
- Utility detection – Improved health and safety and reduced risks by locating underground services prior to intrusive investigations.
- Marine surveys – Hydrographic mapping, bathymetry and lake or river bottom profiling, surficial and subsurface mapping of sea bed sediments, rocks and potential geological hazards, geotechnical evaluation, search and salvage, inspection of marine structures, and sampling.
Each site, and the problem requiring solution, is assessed to ascertain the most suitable geophysical approach. This assessment includes examination of the geology, the historical data, and the physical differences between the target and the surrounding materials.
Once this assessment has been carried out, Earthscan Geoscience may use one or more of the following geophysical survey methods to solve the problem:
- Ground-penetrating radar
- Time- and frequency-domain electromagnetic methods
- Seismic refraction and reflection
- Tomographic methods
- Magnetometry and gradiometry
- DC resistivity, both profiling and sounding
- Borehole geophysical logging including radar and cameras