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Importance and stages of site investigation

Short answer

Site investigation is essential to choose safe, economical foundations, obtain design parameters, and identify problem soils and groundwater. Stages are reconnaissance, preliminary exploration (few borings for general strata), detailed exploration (sampling and testing for design), supplementary investigation during construction, and final report.

Describe in detail the importance of site investigation and the stages of site investigation.

Site investigation (soil exploration) is the process of finding the nature, extent and properties of the soil and rock and the groundwater at a site.

Importance

  • To select a safe and economical foundation type and depth.
  • To get design parameters for bearing capacity and settlement.
  • To find problem soils (soft clay, peat, swelling, collapsible, liquefiable soil) and groundwater.
  • To plan the construction method, dewatering, excavation support.
  • To find construction material sources and the stability of slopes.
  • To avoid failures, delay and cost increases from unforeseen conditions.

Stages

  1. Reconnaissance (desk study and site visit): study maps, geology, aerial photos, past records, and walk over the site.
  2. Preliminary exploration: a few borings/test pits and simple tests to learn the general strata, groundwater and the likely foundation type.
  3. Detailed exploration: more boreholes, undisturbed sampling, field and laboratory tests to get the design parameters.
  4. Supplementary exploration (during construction): extra tests where unexpected conditions appear.
  5. Report preparation with recommendations.

✓ Answer checked by Claude Sonnet 5.5

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