STRENGTH AND DEFORMABILITY OF SPECIFIC SEDIMENTARY AND OPHIOLITHIC ROCKS

The paper deals with the evaluation of strength and deformability of sedimentary rocks and ophiolites based on the processing of laboratory testing results. Characteristic values and their typical range for the parameters σci, Ei , as well as the Modulus Ratio (MR) are presented. These parameters are significant for the estimation of the strength and deformability of the rock mass since σci is basic component for the solution of Hoek-Brown failure criterion and Ei and MR are important components of the latest rock mass deformability expression (Hoek-Diedrichs, 2006). The recent site investigation and laboratory work undergone for the design of numerous tunnels in the Greek territory provided very good and sufficient data, derived from a specifically established database, for the estimation of strength and deformability of specific rocks. These rocks are sandstones and siltstones of flysch and molassic formations, as well as limestones and ophiolites.

SELECTION OF A FIELD TESTING METHOD FOR KARST ROCK MASS DEFORMABILITY BY MULTI CRITERIA DECISION ANALYSIS

The rock mass deformation modulus is an essential parameter for any numerical analysis and prediction of deformation in geotechnical engineering. Experience acquired using a large number of geotechnical projects in Croatia and the world indicates a somewhat unreliable determination of rock mass deformability based on correlation of classification results. The method of field testing for deformability can provide a more reliable insight into rock mass behaviour under loading conditions. The paper presents the most frequently used methods for field testing rock deformability. The benefits and disadvantages are shown of each particular method used in determining criteria and forming a ranking list of test methods using the multi criteria decision analysis. This ranking list of terrain testing for the rock mass stiffness is acquired on the basis of set criteria, assumes guidelines for compiling an exploratory works plan necessary for designing complex geotechnical structures in karst. Appropriate analyses of the sensitivity to changes in the significance of particular criteria was carried out including its effect on selecting the field method for testing karst rock mass deformability.

Methodology for extrapolation of rock mass deformability parameters in tunneling

This article proposes one approach for extrapolation of necessary parameters for numerical analyses in tunnelling. The approach is named as an empirical - statical - dynamical method for extrapolation. The proposed methodology is based on combination of empirical classification rock mass methods, geophysical measurements and direct dilatometer deformability testing on a field. The analyses are prepared for purposes of investigation and design for several tunnels in Republic of Macedonia. One example for dividing of tunnel length in quasi-homogenous zones, as a basis for forming of geotechnical and numerical model that can be a basis for interaction analyses of rock - structures system and stress-strain behaviour of rock massif, is also given. The several original regressive models between rock mass quality, deformability and velocity of longitudinal seismic waves are shown.

Application of analogous models in civil engineering

The paper describes the results of making the mathematical and physical models of the authors, by using analogous methods and materials. There is the mathematical rock mass deformability model as a base for foundation engineering a concrete arch dam and the physical rock slope model which was tested by loading until failure and the results were compared with the calculation procedure. In the first example the correlation is established between the static and the analogous dynamic in situ investigations for creating the mathematical rock mass deformability model. In the second example there is application of the analogous materials for the discontinuity shearing simulation on the physical slope model. The results of the geotechnical in situ investigations and laboratory testing carried out in the Institute for Development of Water Resources "Jaroslav Cerni" in Belgrade were used for making the models.