Test Procedure for the Determination of Maximum Moisture Content to be Expected under Footings Located in Permeable Soil Above Water Table.

Citation

Alwart, Harold John and Servet, Abdurrahim (1937) Test Procedure for the Determination of Maximum Moisture Content to be Expected under Footings Located in Permeable Soil Above Water Table. Master's thesis, California Institute of Technology. doi:10.7907/k6ad-2w08. https://resolver.caltech.edu/CaltechTHESIS:03252025-201053142

Abstract

The problem of determining the bearing value of a soil has long caused considerable trouble among foundation engineers. One of the main features of this problem is the determination of the probable minimum bearing value of a California soil when tested during the summer or dry season. It is a known fact that the bearing value of the soil will vary with the moisture content. It is also quite generally known that the present tests of bearing value do not give true results. By true results are meant, results which accurately check field determinations. There are certain cases in which the saturated tests now in use give value far too low as well as inconsistent values. By means of the tests outlined, the authors believe that more accurate and reliable results may be obtained in the future.

These tests are mainly concerned with the bearing values of soils under shallow footings. Deep footing, cassions and piles are eliminated from the tests. The reason for this being that the authors believe that the more specialized cases should be more thoroughly investigated. However, in the case of the shallow footings, as used for school buildings and homes, a limited amount of investigation and time for testing is required. With this point in mind, work has been concentrated on this point.

As a preliminary step along this line, moisture contents were taken at a number of places before the rainy season began. This was done so that the increase in moisture of a number of definite soils could be obtained and checked in the laboratory. Samples were taken at various depths and places, concentration being in the poorer soils of the district. Later after an unusually heavy rainy season, which it was fortunate to encounter, the sampled places were revisited and the moisture content of the soil again obtained. With this data it was assumed that laboratory checks for these values would hold for any similar soil.

The laboratory work was divided into two main categories. First being the determination of the type of soil in use and its various properties, and the second, the technique and type of test suited for this subject. This first part consisted of the standard tests which are hydrometer and sieve analysis, liquid and plastic limits, shear, compression, shrinkage and sp-gravity. The second part was split up into three divisions, per collation, rainfall and capillary rise tests. All results were reduced to a common base, but due to the large number of variables, such as compaction, types of soil, density, etc. and the limited time, this could not be carried to the completion desired by the authors.

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