Civil and Building Engineering.

1 Introduction: In a remarkable effort, the late Dr. M. Juul Hvorslev, working at the Waterways Experiment Station in Vicksburg, Mississippi, and supported by a number of other agencies, presented a comprehensive document on subsurface exploration and sampling of soils for purposes of civil engineering (Hvorslev,
1949). The document has been reprinted by the Waterways Experiment Station and remains a valuable reference.

The term undisturbed is used to designate samples of high quality. TheASTM uses the term relatively undisturbed in describing the use of sampling with thin-walled tubes (ASTM-D 1587). Disturbance of samples is due to a number of factors: change in the state of stress as the sample is retrieved from the soil, especially if the sample contains gas; disturbance due to resistance against the sides of the sample as it enters the sampling tube; disturbance during transportation to the laboratory; and disturbance as the sample
is retrieved from the sampling tube.

Disturbance due to the presence of gas in soils is difficult to overcome.

Methods must be implemented to prevent the specimen from expanding throughout the sampling, transportation, trimming, and testing periods. A most severe problem involves the sampling and testing of hydrates that occur in frozen layers at offshore sites.

Sampling disturbance due to resistance against the sample as it is pushed into the sampling tube can be significant. Hvorslev (1949) includes some remarkable photographs of samples that have been distorted in the sampling process (pp. 95, 96, 98, 104, 106, 112, 115, 116). In accounting for the effects of sampling disturbance, Ladd and Foott (1974) proposed experimental procedures for use in the laboratory to determine the strength of most soft, saturated clays.

2 Sampling with Thin-Walled Tubes: The ASTM has published a detailed standard (1587) for thin-walled tube sampling of soils...

3 Sampling with Thick-Walled Tubes: Exploratory investigations can be made using a thick-walled sampler that has a split barrel...

 4 Sampling Rock: Samples of rock can be taken by core drilling, as shown in Figure 4.7, and the standard practice for diamond core drilling for site investigation is given in ASTM D 2113, as shown in Figure 4.6...