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KIRTLAND AIR FORCE BASE ALBUQUERQUE, NEW MEXICO ...

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APPENDIX B<br />

that if gravel or rock fragments are broken by the sampler or if rock fragments are logged in the tip, the<br />

resulting blow count will be erroneously high, reflecting a higher density than actually exists. This<br />

should be noted on the log and referenced to the sample number.<br />

The consistency of cohesive soils is determined by performing field tests and identifying the consistency<br />

as shown in Figure B1.1-2. The consistency of cohesive soils is determined either by blow counts or<br />

most accurately by a pocket penetrometer or field Torvane device in accordance with ASTM D2573-72–<br />

Method for Field Vane Sheer Text in Cohesive Soil. The SPR can be applied to cohesive soils as follows:<br />

Designation<br />

SPR (blows per ft)<br />

Very soft ........................................................................ 30<br />

The pocket penetrometer method is conducted on a selected sample of the soil, preferably the lowest 0.5<br />

ft of the sample in the split-spoon sampler. The sample should be broken in half and the penetrometer<br />

pushed into the end of the sample to determine the consistency. Do not determine consistency by<br />

attempting to penetrate a rock fragment. If the sample is decomposed rock, it is classified as a soft,<br />

decomposed rock fragment rather than a hard soil. The pocket penetrometer or Torvane may be used in<br />

the conjunction with blow counts to determine cohesive soil consistency.<br />

Soil Component<br />

In nature, soils are comprised of particles of varying size and shape and are combinations of the various<br />

soil types. Figure B1.1-2 lists grain size classifications to be used in describing soils or rocks. The<br />

following terms are useful in the description of soil components:<br />

The Identifying Proportion of the Component Defining Range of Percentages by Weight<br />

trace ............................................................................... 0-10 percent<br />

Moisture<br />

little ................................................................................ 11-20 percent<br />

some ............................................................................... 21-35 percent<br />

―and‖ ............................................................................. 36-50 percent<br />

Moisture content is estimated in the field according to four categories: dry, moist, wet, and saturated. In<br />

dry soil, there appears to be little or no water. Saturated samples obviously have all the water they can<br />

hold. Moist and wet classifications are somewhat subjective and often are determined by the individual‘s<br />

judgment. A suggested parameter for judging this in a fine-grained soil would be calling a soil wet if<br />

rolling it in the hand or on a porous surface liberates water, i.e., dirties or muddies the surface. Whatever<br />

method is adopted for describing moisture, it is important that the method used by an individual remains<br />

consistent throughout an entire drilling job.<br />

Laboratory tests in accordance with ASTM D2216 or field tests for water content should be performed if<br />

the natural water content is important.<br />

Kirtland AFB<br />

SOPs for Field Investigations B-16 April 2004

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