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In your experience, what items that should be in geotechnical reports are sometimes missing, and what do you do in that case, can you provide example? Do we look at codes or make best guess and based on what? Or do we need to make our own soil testing? Please give example / examples from your experience or what you know, if you could...

Edit: This question was closed by the moderators stating that it is opinion based. However, this is the nature of this question. Missing items in geotechnical reports occur often and the only way to discuss this is through opinion of experienced engineers. See the answer below, which was given before the moderators closed the question, which provides a very informative answer. This question should stand open which would provide valuable information to readers. This question is a useful discussion for geotechnical and structural engineers. Asking for typical missing items can not be a fact based question in nature in the first place. Experiences are also valuable.

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A structural engineer should never conduct their own soil testing unless being supervised by a competent person. This is not your area of expertise, let the geotechnical engineer do their job.

Generally the geotechnical engineer should outline any risks specific to the site that way other engineers can design for them. An example of this would be hydrostatic pressure, radon in the soil, expansive soils, etc.

However I have come across geotechnical reports that lack content. Usually the report specifies their recommended foundation system (1-2 different types) based on the soil conditions on site. They may also understand that certain engineers tend to use nonconventional foundation systems (such as a post-tension slab on grade) and cater the report specifically to that engineer.

Minimum info to be included in the reports for each foundation system are as follows:

Spread Footings:

  1. Bearing capacity
  2. Sliding friction coefficient
  3. Minimum dead load
  4. Frost Depth

Drilled Piers or Caissons:

  1. Bearing Capacity at different depths
  2. Side friction coefficients at different depths
  3. soil stiffness properties at different depths (for lateral loading)
  4. minimum embedment into bedrock
  5. minimum diameter

Mat Slab or Raft:

  1. Bearing capacity
  2. Soil spring factor (k)
  3. Frost Depth

Foundations Walls

  1. Bearing Capacity
  2. Active, at rest, and passive earth pressures
  3. Sliding friction coefficients
  4. recommended drainage systems behind the walls
  5. Frost depth

If they're missing info just reach out to them and ask for it. They're only human.

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