Types Of Samplers | What are the types of samplers?
Open-Drive Sampler.
It consists of a steel tube with a screw thread at each end. The lower end is usually fitted with a cutting shoe but sometimes with an extension piece.
The top end is fitted with a sample head, which includes a non-reversible valve.
Non-return The valve allows air and water to escape when the specimen enters and closes the specimen to the surface, thus retaining the specimen inside the tube (Figure 18.9).
This is the simplest and most common type of model.
Thin-Wald Sampler.
Thin-walled models can be used to obtain undisturbed specimens in soft clay and plastic silt (IS: 11594, 1985).
However, No separate cutting shoe is attached to the lower end, but the bottom of the specimen itself is machined to act as a cutting edge (Fig. 18.10).
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High-quality undisturbed samples are possible if the soil is not disturbed during Ar <10% and boring operation. This model can be used more conveniently in experimental pits and shallow boreholes.
Split-Spoon Sampler.
This includes providing a longitudinally split tube or barrel with a shoe and sampler head for air release (IS: 9640, 1980).
Therefore, The splitting element of the specimen allows the sample to be opened for testing and for further dispersion in sample containers (Fig. 18.11).
Samples obtained using this model are rated as representative. This model is suitable for sands and is only used in the standard penetration test (SPT).
Moreover, Split-quick models can be provided with a liner, thin metal, or plastic tube embedded in a split spoon, in this case, called a composite model.
However, The purpose of the liner is to protect the specimen during handling, shipping, and storage. Piston Sampler. For very soft alloys and clays, piston models are quite useful.
Moreover, These include a thin-walled tube, which includes a piston device, which helps push the thin-walled tube from the bottom of the boring to unstoppable soil (IS: 10108, 1982).
However, The piston is locked in the bottom position and the sample is lowered to the bottom of the borehole. The piston is provided with a seal that prevents water and debris from entering.
When it is unlocked, the tube is driven into the soil for the entire journey of the piston.
Since, After locking the piston on the top of the tube, the entire assembly is lifted back to the surface (Fig. 18.12).
The specimen is separated from the head and piston. However, It is then sealed at both ends.
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