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Building Design and Construction Handbook - Merritt - Ventech!

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6.14 SECTION SIX<br />

FIGURE 6.1 Soil Samplers (no. 1 is the California Sampler in an open condition,<br />

no. 2 is a Shelby Tube, <strong>and</strong> no. 3 is the St<strong>and</strong>ard Penetration Test sampler.)<br />

1. Altered Soil. During the boring operations, soil can be altered due to mixing<br />

or contamination. For example, if the boring is not cleaned out prior to sampling,<br />

a soil sample taken from the bottom of the borehole may actually consist of cuttings<br />

from the side of the borehole. These borehole cuttings, which have fallen to the<br />

bottom of the borehole, will not represent in-situ conditions at the depth sampled.<br />

In other cases, the soil sample may become contaminated with drilling fluid, which<br />

is used for wash-type borings. These types of soil samples that have been mixed<br />

or contaminated by the drilling process should not be used for laboratory tests<br />

because they will lead to incorrect conclusions regarding subsurface conditions.<br />

Soil that has a change in moisture content due to the drilling fluid or heat generated<br />

during the drilling operations should also be classified as altered soil. Soil that has<br />

been densified by over-pushing or over-driving the soil sampler should also be<br />

considered as altered because the process of over-pushing or over-driving could<br />

squeeze water from the soil.<br />

2. Disturbed Samples. Disturbed soil is defined as soil that has been remolded<br />

during the sampling process. For example, soil obtained from driven samplers, such<br />

as the St<strong>and</strong>ard Penetration Test spilt spoon sampler, or chunks of intact soil brought<br />

to the surface in an auger bucket (i.e., bulk samples), are considered disturbed soil.<br />

Disturbed soil can be used for numerous types of laboratory tests.

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