Rock materials

8 marzo 1996 conferenza corso ORGL pag. 2 di 33 EFFETTO MIGLIORAMENTO PER Intervento Materiale Confinamento Resistenza al taglio Deformabilità Infilaggi di protezione, paratie berlinesi Detrito SI Drenaggi Roccia/ Detrito SI Iniezioni cementanti Detrito/ Roccia fratturata SI SI Pretaglio Argille SI Jet grouting Detrito A volte SI SI Bullonatura Roccia fratturata/ Detrito SI SI SI Congelamento Detrito SI SI

It is not clear exactly how a rock fails, either in terms of the precise details of each micro crack initiation and Propagation or in terms of the total structural breakdown as many micro cracks propagate and coalesce. In both cases, the process is extremely complex and not subject to convenient characterization through simplified models. Nevertheless, as engineers, we should like some measure of the failure properties and the ability to predict when failure will occur. The strength criteria of rock materials can be divided into three major groups: theoretical failure criteria, experimental and curve fitting based criteria. And the last set of them is composed of two mentioned sets of failure criteria. The Mohr-Coulomb criterion expresses the relation between the shear stress and the normal stress at failure. The plane Griffith criterion which locates in theoretical group, express the uniaxial tensile strength in terms of the strain energy required to propagate micro cracks. One of the most widely used empirical strength criterion for intact rock and rock masses is Hoek-Brown Criterion. In this paper we present outlines of these criteria and focus on the Hoek-Brown criterion. The method of research is based on books and articles published in authoritative publications and journals. As a result, various types of rock failure criteria are classified and some useful suggestions regarding presented criteria have been presented. Empirical criteria, Specially Hoek and Brown Criterion, Which are in good correlations with real conditions, can be significantly much more efficient in the rock mechanics problems.

En este artículo se describe una campaña sistemática de ensayos no-destructivos con el martillo de rebote tipo Schmidt-L, que se hizo en una placa de sodalita de 0,05 m de espesor en un área de ensayo cuadrada de 2,0 m de lado. Esta investigación reveló que la roca ornamental estudiada tiene ---en lo que respecta a su resistencia mecánica--- una variabilidad inherente al tipo de material en sí y también una variabilidad relativa a su posición espacial, ésta última con claros signos de una dirección preferencial. Estas variabilidades pueden detectarse por la aquí propuesta campaña de ensayos y el uso de la geoestadística; conclusiones que son útiles para el control de calidad de placas de material rocoso destinadas para fines ornamentales.

PACS 91.60.-x, 83.80.Nb

Maltese Cross Church is one of the rock-cut churches in Cappadocia, Goreme Open Air Museum. The museum is listed as a World Heritage Site by UNESCO and the rock structures in it have problems on their material and structure, which endanger their existence. The aim of this study is analysing the problems of a rock-cut church; Maltese Cross Church, in the museum and suggesting solutions for damages according to the data obtained with in-situ damage assessment, laboratory and in-situ tests which were done during the winter and summer season in 2014. Rock samples of the church were assessed to have their mechanical, physical, chemical, petrographic and mineralogical characteristics and the deteriorations of the rock material was searched. And, suggestions to overcome the problems are proposed.