**Published:** Jan 1952

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**Source: **STP126-EB

When investigating the probable settlement of a structure it is customary to perform a series of consolidation tests on undisturbed samples of the compressible material underlying the foundation. The purpose of such a testing program is to provide the engineer with the necessary data for evaluating the probable compression and the time rate of compression of the actual soil strata. Normally, the consolidation tests will be performed in a laboratory where temperatures may vary from 60 to 80 F. However, specimens used for consolidation tests are frequently taken at a depth where temperatures sometimes vary from 40 to over 80 F. The question then arises as to what effect this difference in temperature, between laboratory test conditions and *in situ* condition, might have on the compressive characteristics of the material and whether or not the effect is of significant proportions. The consolidation characteristics of a soil are normally evaluated by application of the Terzaghi theory of primary consolidation, which is based on a number of, simplifying assumptions and approximations. To estimate the rate of compression from this theory, it is necessary to determine the coefficient of consolidation which is expressed by the formula: *k* = coefficient of permeability (assumed constant for each load increment), *e* = void ratio, usually the average for any load increment, *a*^{v} = coefficient of compressibility, and γ = unit weight of water From this relationship it can be seen that the coefficient of consolidation is directly proportional to the coefficient of permeability. It is known that permeability is related to viscosity which, in turn is related to temperature. Hence, it can be concluded that the coefficient of consolidation will depend on the temperature at which consolidation occurs. A closer analysis will show that the coefficient of consolidation should be directly proportional to temperature.

**Author Information:**

Finn, F. N.*Junior Research EngineerLecturer in Civil Engineering, Institute of Transportation and Traffic EngineeringUniversity of California, Berkeley, California*

**Committee/Subcommittee:** D18.02

**DOI:** 10.1520/STP48297S