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| 3 |
Undisturbed samples: |
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It retains as closely as practicable the true insitu structure and water content of the soil. For undisturbed sample the stress changes can not be avoided. The following requirements are looked for: |
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No change due to disturbance of the soil structure, |
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No change in void ratio and water content, |
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No change in constituents and chemical properties. |
| 4 |
Requirement of good sampling process |
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Inside clearance ratio  |
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The soil is under great stress as it enters the sampler and has a tendency to laterally expand. The inside clearance should be large enough to allow a part of lateral expansion to take place, but it should not be so large that it permits excessive deformations and causes disturbances of the sample. For good sampling process, the inside clearance ratio should be within 0.5 to 3 %. For sands silts and clays, the ratio should be 0.5 % and for stiff and hard clays (below water table), it should be 1.5 %. For stiff expansive type of clays, it should be 3.0 %. |
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Area ratio  |
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