Geo-technical tests are performed by geo-technical engineers, geo-technical technicians or engineering geologists to understand the characteristics such as the physical properties that exist underneath a work site. Geo-technical testing will include a walk around of the surface conditions as well as one or more of a variety of tests.
Tests generally fall into 4 categories, test pits, trenching, boring and in-situ testing.
Test pits are much like you would expect, a pit is dug either manually or with an excavator in order to reveal the sub-surface conditions to the depth desired.
Trenching is similar to Test pits except that in this case, the pit is elongated over some distance in order to establish how the sub-surface conditions change over various parts of the work site. A range of soil samplers can be used to extract test samples including shovels, hand-driven augers, split-spoon samplers, modified California samplers and Shelby tube samplers.
Borings, usually small-diameter borings, provide the opportunity to physically remove soil or rock samples for testing. Borings provide the advantage of letting you ‘see’ the actual materials, but for certain types of soils, the very act of boring can disturb the soil conditions and the samples extracted may not represent what the conditions will actually be for building and supporting structures since it is unscientific and void of actionable data.
Generally, soil samples from the above tests are taken to a lab where they are evaluated.
In-situ (in the situation, or at site) testing methods include penetration tests such as Standard Penetration Tests (SPT), which penetrate via drilling, and various Cone Penetration Tests, which penetrate via direct push . These tests measure the physical properties of the subsurface soil directly, without removal. This provides the advantages of generating a more accurate reflection of conditions underground as well as avoiding the necessity of sending samples out for lab testing.
The right test should be specified for the right situation. By understanding the different types of tests available and the advantages of each, you can help your clients to understand the advantages of CPT and expand your business while helping your clients to generate better results, faster and less expensively.