AASHTO T 207:12(2020) Standard Method of Test for Thin-Walled Tube Sampling of Soils.
This method covers a procedure for using a thin-walled metal tube to recover relatively undisturbed soil samples suitable for laboratory tests of engineering properties, such as strength. compressibility, permeability, and density. Thin-walled tubes used in piston-. plug-, or rotary-type samplers. such as the Denison or Pitcher, must comply with the portions of this practice that describe the thin-walled tubes (Section 5.3).
Note 1—This method does not apply to liners used within the above samplers.
Not all tubes specified in this method may be of sufficient diameter to perform all strength or consolidation testing. Refer to the appropriate test method for the minimum sample size to determine if the tube will be appropriate for that test.
This method is used when it is necessary to obtain a relatively undisturbed specimen suitable for laboratory tests of engineering properties or other tests that might be influenced by soil disturbance.
Drilling Equipment—Any drilling equipment may be used that provides a reasonably clean hole, that minimizes disturbance of the soil to be sampled, and that does not hinder the penetration of the thin-walled sampler. Open borehole diameter and the inside diameter of driven casing or hollow stem auger shall not exceed 3.5 times the outside diameter of the thin-walled tube.
5.2. Sampler Insertion Equipment- shall be adequate to provide a relatively rapid continuous penetration force. For hard formations it may be necessary, although not recommended, to drive the thin-walled tube sampler.
5.3. Sampler Head- serves to couple the thin-walled tube to the insertion equipment and, together with the thin-walled tube, comprises the thin-walled tube sampler. The sampler head shall contain a suitable check valve and a venting area to the outside equal to or greater than the area through the check valve. In some special cases, a check valve may not be required, but venting is required to avoid sample compression. Attachment of the head to the tube shall be concentric and coaxial to assure uniform application of force to the tube by the sampler insertion equipment.
5.4. Thin-Walled Tubes— should be manufactured as shown in Figure 1. They should have an outside diameter of 50.8 to 127.0 mm (2 to 5 in.) and be made of metal having adequate strength for use in the soil and formation intended. Tubes shall be clean and free of all surface irregularities including projecting weld seams. Other diameters may be used, but the tube dimensions should be proportional to the tube designs presented here.AASHTO T 207 pdf download.