Consider the following statements: 1. A recovery ratio of less than 1 implies that the soil has compressed. 2. A recovery ratio of greater than 1 implies that the soil has swelled. 3. A recovery ratio of less than 1 implies that the soil has swelled. 4. A recovery ratio of greater than 1 implies that the soil has compressed. Which of these statements is/are correct?
1 and 2
Understanding Soil Recovery Ratio
The question asks us to evaluate statements relating the recovery ratio of soil to its behavior, specifically compression and swelling. The recovery ratio typically relates the amount of deformation that is recovered (rebound) after a load is removed to the initial deformation caused by the load.
Analyzing the Statements
Let's analyze each statement based on the common understanding of soil deformation:
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Statement 1: A recovery ratio of less than 1 implies that the soil has compressed.
If the recovery ratio is less than 1 (let's denote it as RR < 1), it means the deformation recovered upon unloading is less than the deformation that occurred under loading. This indicates that some of the deformation is permanent, meaning the soil has undergone irreversible compression. Therefore, this statement is considered correct.
We can think of it like this: If you compress a spring and it only partially returns to its original length, the part that didn't return is permanent compression.
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Statement 2: A recovery ratio of greater than 1 implies that the soil has swelled.
If the recovery ratio is greater than 1 (RR > 1), it means the deformation recovered upon unloading is greater than the deformation that occurred under the initial loading. In the context of soil mechanics, this suggests that the soil not only returned to its original state but expanded beyond it. This expansion is often referred to as swelling. Thus, this statement is also considered correct in the context of the question's intended meaning.
Imagine compressing a material, and upon release, it not only returns to its original size but expands slightly more. This excess expansion could be interpreted as swelling.
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Statement 3: A recovery ratio of less than 1 implies that the soil has swelled.
This statement contradicts the logic explained for Statement 1. A recovery ratio less than 1 signifies incomplete recovery, indicating permanent compression, not swelling. Hence, this statement is incorrect.
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Statement 4: A recovery ratio of greater than 1 implies that the soil has compressed.
This statement contradicts the logic explained for Statement 2. A recovery ratio greater than 1 suggests the soil's expansion upon unloading exceeded the initial compression, which is characteristic of swelling, not compression. Hence, this statement is incorrect.
Conclusion on Correct Statements
Based on the analysis, statements 1 and 2 correctly describe the implications of the recovery ratio in relation to soil behavior.
- A recovery ratio < 1 means the soil experienced permanent compression.
- A recovery ratio > 1 suggests the soil experienced swelling (or rebound greater than initial compression).
Therefore, the correct statements are 1 and 2.
Important Questions from Site Investigation and Sub-Soil Exploration
In order to minimize sampling disturbance the area ratio A r,\(\left( {{{\rm{A}}_{\rm{r}}} = \frac{{{\rm{D}}_{\rm{e}}^2 - {\rm{D}}_{\rm{i}}^2}}{{{\rm{D}}_{\rm{i}}^2}}{\rm{\;}}} \right)\) should be
Shelby tube is one of the most widely used devices for:
Which one of the following is NOT a soil exploration technique?
If the sampler tube is pushed at the bottom of the bore hole to a distance of 585 mm with length of the sample recovered being 535 mm. Then the value of recovery ratio is ______.
If the inside diameters of the cutting edge and sample tube are 68 mm & 70 mm respectively and 76 mm & 74 mm are the outside diameters of the cutting edge and sample tube respectively, then outside clearance of the sampler is _______.
