Geophysical testing is often used as part of the initial site exploration phase of a project and/or to provide supplementary information gathered by widely spaced observations (i.e., borings, test pits, outcrops, etc.). Is. Geophysical testing can be used to establish the stratification of subsurface material, the profile of the top of the base, the depth of the groundwater, the extent of soil types, the repeatability of hard soil and rock, and the presence of voids, buried pipes and depths. presence of. existing foundation. Data from geophysical testing should always be correlated with information on direct methods of exploration.

There are several different geophysical in-situ tests that can be used for stratigraphic information and in the determination of engineering properties. The two most common methods are:

  1. seismic methods
  2. electrical methods

Read also: Electrical resistivity test of soil

Advantages of Geophysical Testing

Geophysical testing offers some notable advantages and some disadvantages that must be considered before recommending a technique for a specific application. The advantages are in brief as follows:

  • Many geophysical tests are non-invasive and thus provide significant advantages in cases where conventional drilling, testing and sampling is difficult (eg, gravel deposits, talus deposits) or where potentially contaminated soil is in the subsurface. can.
  • In general, geophysical testing covers a relatively large area, thus providing the opportunity to characterize large areas with few tests. It is particularly suitable for projects that have a larger longitudinal limit than the lateral limit (such as for new highway construction).
  • Geophysical measurements assess soil and rock characteristics at very small strains, typically on the order of 0.001 percent, thus providing information about the truly elastic properties.
  • For the purpose of obtaining information on the subsurface, geophysical methods are relatively inexpensive when considering the relative cost of the larger areas on which information can be obtained.

Limitations of Geophysical Testing

Some common disadvantages of geophysical methods include:

  • Most methods work best for situations in which there is a large difference in hardness between adjacent subsurface units.
  • If normal stratigraphy consists of hard materials over soft materials, it is difficult to develop good stratigraphic profiling.
  • The results are usually interpreted qualitatively and therefore useful results can only be obtained by an experienced engineer or a geologist familiar with the particular test method.
  • Requires specialized equipment (compared to more traditional subsurface exploration equipment).

Read also: Electrical resistivity test of soil

Er. Mukesh Kumar

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Er. Mukesh Kumar is Editor in Chief and Co-Funder at ProCivilEngineer.com Civil Engineering Website. Mukesh Kumar is a Bachelor in Civil Engineering From MIT. He has work experience in Highway Construction, Bridge Construction, Railway Steel Girder work, Under box culvert construction, Retaining wall construction. He was a lecturer in a Engineering college for more than 6 years.