Standard Penetration Test (SPT) and Split-Barrel Sampling
This sampler is commonly referred to as a split spoon sampler. Used for sampling with Automatic Drop Hammers and SPT Systems. The SPT blow count is the number of blows of the automatic hammer required to advance the split barrel sampler 12 inches (305 mm).
When the level of interest is reached, the core barrel is removed and the SPT is introduced to carry on a test process in the bottom of the borehole.
The test is carried out by lowering the SPT sampler and the rods to the bottom of the borehole. Once there, the automatic trip hammer is placed on the upper part of the rods and the initial penetration is recorded. Then the Sampler is driven an initial distance of 150 mm, called “seat penetration”, striking with the free fall hammer, 63.5 kg, from a height of 760 mm and recording the number of hammer blows necessary to drive these first 150 mm (N0).
Nest, 300 mm are driven in the same way in two sections of 150 mm and the number of hammer blows required in each of these sections (Nn and Nn+1) is recorded. If a total of 50 hammer blows is reached to reach the length of the test, the test is finished.
The SPT also offers a sample for laboratory analysis.