Propriedades mecânicas de solos algumas reflexões sobre ensaios de laboratório e ensaios in situ

Abstract

The historical background and the present trends of the two fundamentals methods

- laboratory and in situ determination of the mechanical properties of soils - are presented.  The advantages and shortcomings of each method are discussed. Concerning laboratory tests the more important sources of error are related with the disturbances of samples and the need of a convenient size for a given sample in order to assure the representativness of the soil mass; on the other hand the conditions of laboratory tests are well known and easy to be changed and controlled with accuracy. Concerning in situ tests, in general, improvements are obtained regarding the effects of disturbance; but the volume of soil interested by the test is small, not assuring true representativness of the properties of the soil mass as a whole.

Laboratory tests seem well fitted to study the phenomenology of rheologic processes of soil masses. ln sítu tests, due to the smaller disturbances involved, are many times the best way to assess the quantitative determination of the mechanical properties of a given soil mass.  A surpassing synthesis seems possible performing systematic observations of buildings and soil masses in order to obtain corrective factors for the transfer from test results to actual soil properties.