LABORATORY EXERCISE 3
PREPARATION OF UNDISTURBED SOIL SAMPLE FOR TEST
Objective:
This laboratory exercise is performed to know the process and the importance in
preparing undisturbed soil samples for physical test.
Significance:
The preparation of undisturbed soil sample is important in that the soil sample represents
the actual soil structure found in the ground. The behavior of soil under load will be determined
from this sample. The nearest cases of undisturbed sample are those obtained with minimum
disturbance; that is, both the natural density and water content are preserved as much as
practicable. Such samples are necessary for density, permeability, consolidation, and various
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shear tests.
Undisturbed samples are obtained by two methods, “open pit” and tube sampling. In the
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former, a big chunk is carefully excavated from an exposed surface of the ground with the use of
common digging tools. In the latter, thin-walled tubes are drawn deep into the ground to extract
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the sample. Immediately after removal, the samples are covered with protective coating such as
paraffin or other waxes. rs e
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Equipment:
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- soil lathe
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- wire saw, with one fine wire for final trimming
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- sharp knife
- miter box
- extruder for tube samples
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Size of Sample:
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1. Consolidation → 1 sample, 2-in. height and 2 ¾ in. diameter
2. Unconfined Compression → 2 samples, 4–7 in. height and 2–3 ½ in. diameter
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3. Triaxial Shear → 3–5 samples, 4–7 in. height and 2–3 ½ in. diameter
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Procedure:
The preparation of samples should be done in a humid room to minimize moisture loss.
Tube samples should be extruded carefully and in the same direction as when obtained.
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1. Remove the protective coating by cutting with sharp knife.
2. Cut from the field sample a test specimen which is slightly larger than the standard
size required in the test.. Use either a wire saw or a sharp knife whichever is more
appropriate for least disturbance.
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3. Trim the specimen to standard circular cross section with the soil lathe and a finer
wire saw.
4. Place specimen in the miter box and cut to a standard height. Both ends should be
perpendicular to the sides of specimen.
5. Measure the exact dimension for specimen using a caliper.
Precautions in the preparation of an undisturbed sample:
1. Never handle the specimen with your hands. Use a cellophane or wax paper.
2. When transporting a specimen, support it over the entire length.
3. Clean the wire saw efter every cut to remove soil sticking to it.
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https://www.coursehero.com/file/23704208/Lab-03-Unedited/
PREPARATION OF UNDISTURBED SOIL SAMPLE FOR TEST
DATA SHEET
Date Performed: __________________
Date Presented: __________________
Performed By: __________________
Group No.: __________________
Sample Description: __________________
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Undisturbed Soil Sample
Test Quantity Size
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Consolidation
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Unconfined Compression
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Triaxial Shear
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Remarks:
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______________________________________________________________________________
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This study source was downloaded by 100000798397300 from CourseHero.com on 04-17-2021 03:30:42 GMT -05:00
https://www.coursehero.com/file/23704208/Lab-03-Unedited/
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