February 23, 2017

Top 5 Things that Need to Be Sampled During a Geotech Assessment



In order to understand the risks posed by rock and soil, a geotechnical assessment is required. Through an assessment, you can learn more about soft or weak ground, groundwater, and the potential for landslides and sink holes in your work area. However, there are a few samples that need to be collected in order for you to gauge these risks. Here are five things that need to be sampled during a thorough geotech assessment.

1. Surface-Level Soil

A soil test is necessary to determine whether the land is contaminated before work begins. A piece of property may be contaminated with pollutants from prior structures, or by work that has been conducted in the area in the past. A sieve analysis, which takes place in a lab, can help determine the size and number of particles in a patch of soil. This information can help you learn whether your soil is suitable for use in concrete mixing.

2. Remolded Soil

Remolded soil is typically used in an expansion index test to determine the swelling potential of compacted soil. However, EI is not indicative of specific field conditions, such as soil density, water content, and in-place soil structure.

3. Rock

In the event that a project is being constructed over a substantial amount of rock, the material may need to undergo a triaxial shear test. This type of test determines how much stress the material can handle under pressure. There are also varieties of the test that can be conducted to gauge the rock in consolidated drained or undrained situations.

4. Sand

Sand can be tested for moisture content prior to beginning the building process. Similar to soil, tests can be used to determine sand’s particle density, natural moisture content, dry density, and much more before a project is launched. This may be indicative of its ability to withhold the foundation of a building.

5. Groundwater

Groundwater testing can help determine the impact of potentially polluted water on a project. Pumping tests, in particular, can be used to determine a number of factors, including water flow and the mass permeability of water-bearing soils. Additionally, project managers can get a better understanding of where to create new water supply wells and open loop geothermal systems.

A geotechnical assessment is a relatively low-cost, low-impact step a project manager can take to reduce potential liability while working on an unidentified site. Many government agencies require geotech assessments before work is conducted in specific areas. With information from a geotech assessment, individuals can provide everyone from contractors to designers with sufficient details prior to beginning construction.

A typical geotech assessment will contain the results of various field explorations and laboratory tests. Project managers can specify what items they would like to be tested in addition to the standards, such as soil and water, prior to requesting an assessment.

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