Constructive Similarity of Soils

Abstract eng:
The soil and rock variability is a constitutive characteristic of geotechnical materials and it is important to know utmost on it. This knowledge is necessary for a regular and solid calibration both the Limit State Design theory and, of course designs according to EC 7-1. The most important in-put data for the Ultimate Limit State Design are data of shear strength and unit weight which are usually for designs deciding. Behaviour and bearing capacity of soil/rock structures and their interaction with solid engineering structures depend mostly on these properties. The mentioned reasons led to the establishment of a database of physical properties of soils in solid and reliable laboratories tested and to concentrating on shear strength and unit weight. The database is supported continuously a number of years at the Institute of Theoretical and Applied Mechanics of the Czech Academy of Sciences. Is the soil variability so variable like we imagine ourselves? It is solved in the paper using a similarity theory of soils. The paper uses summed database data and deals with the statistical analysis of a similarity of the single soil groups taking use of the database to date. The analysis could provide a better quantitative view at a possible influence of soil variability in geomechanics and in geotechnical design. An idea of the constructive soil similarity is derived from the similarity theory of numerical models. It is applied its transformation for soil masses only due to editing the parameters of geometrical similarity in Eq.1 and 2 out. Then we get following expressions for similarity of materials of the analysed masses: k_π=c/γ k_π=c/γ tan φ where similarity parameters k_π and k_λ have a dimension of length in [m] and denotation of other parameters is the same as in Eq.1 and 2. The soil database of Institute of Theoretical and Applied Mechanics of the Czech Academy of Sciences is continuously developed and is available at Internet address: www.itam.cas.cz/lide/koudelka. The statistical quantity values of basic design input properties of soils (unit weight, top effective shear strength) according to the database ITAM 2010 in Tab.1 (see the Paper) are relevant to the statistical values of constructive similarity parameters in Tab.2 (see the Paper incl. Fig.1). Sample sets representing single classes are sufficient for the statistical analysis except of classes S1, F1 and F2 and these have not been analysed as well as gravel soils. The similarity parameters k_π and k_λ provide an opportunity of a better and more general evaluation of soils. The evaluation can be independent on geotechnical structures and their geometry or, on the contrary can be filled with the geometrical similarity parameter h in (e.g. slope height, foundation width, pile length, depth).

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