The correct answer is: D. none of the above
Direct measurement of permeability of the specimen at any stage of loading cannot be made in either a fixed ring type consolidometer or a floating ring type consolidometer.
A fixed ring type consolidometer is a device used to measure the consolidation of a soil specimen. The specimen is placed in a ring that is fixed in place, and the water pressure is applied to the top of the specimen. The consolidation of the specimen is then measured as a function of time.
A floating ring type consolidometer is a device used to measure the consolidation of a soil specimen. The specimen is placed in a ring that is free to float on the water in the consolidometer. The water pressure is applied to the top of the specimen, and the consolidation of the specimen is then measured as a function of time.
In both types of consolidometers, the permeability of the specimen is not measured directly. Instead, the permeability is calculated from the consolidation data using Darcy’s law. Darcy’s law states that the flow rate of water through a soil is proportional to the hydraulic gradient and the permeability of the soil.
The hydraulic gradient is the change in water pressure divided by the change in distance. The hydraulic gradient is calculated from the consolidation data.
The permeability of the soil is a property of the soil that is difficult to measure directly. Therefore, it is usually calculated from the consolidation data using Darcy’s law.