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The lasting success of any construction project depends on the design of an adequate foundation. Taller buildings—longer bridges—bigger dams—increased highway loading—have all played their part in the demand for more accurate foundation investigation. The design of any foundation results from a careful study and evaluation of the reports on the underlying materials. Therefore, the accuracy of the information obtained concerning the sub-surface soil profile is directly related to the type of equipment used to recover each sample.

As the soil stratas vary so also the equipment used and the procedure followed must be changed to insure the recovery of a sample which is representative of the material penetrated. At times a visual examination of the recovered sample is sufficient while at other times the sample must be subjected to a battery of laboratory tests. Grain size, moisture content, shear properties, shrinkage limits, consolidation properties, permeability, penetration resistance, and the specific gravity are of primary importance in the laboratory analysis of the soil being tested. The evaluation of the tests form the basis for the design criteria.

The type of soils information desired has a direct bearing on the sampling methods employed. To determine only the general characteristics of the soil, samples recovered by the use of a continuous flight auger or by drive sampling are usually sufficient. However, where it is desirable to perform extensive laboratory tests, relatively undisturbed samples such as are obtained by thin wall samplers may be necessary.