SUMMARY

This work is intended as a contribution to the improvement of the ISRM suggested me thod for shear tests. On one hand a more precise definition of shear test techniques was studied, particu larly as regards laboratory tests, in such a way that a larger number of tests can be carried out in the same time without loss of accuracy and with the same costs; on the other hand an analysis was made of the influence exerted by the obliquity of the sheared surface and by the execution of several sliding tests on the same surfaces on the charac teristics of shearing.

RESUME

Ce travail cherche à contribuer à une meilleure adaptation de la methodologie sugge re par la SIMR pour les essais de cisaillement. On etudia, donc, d'un cete une plus precise definition des techniques de realisa - tion des essais de cisaillement, surtout ceux au laboratoire, de façon à ce qu'il soit possible de realiser un plus grand nombre d'essais pendant le même temps, sans perte de precision et avec les memes coats; d'un autre côte on verifia les influences, sur les ca racteristiques de cisaillement, de l'obliquite de la surface de cisaillement et de lã realisation de plusieurs essais de glissement sur les mêmes surfaces.

ZUSAMMENFASSUNG

Die vorliegende Arbeit ist als Beitrag zu einer zukuenftigen Verbesserung der. von der IGFM vorgeschlagenen Methode zur Ausfuehrung von Scherversuchen gedacht. Einerseits wurde eine praezisere Definition der Ausfuehrungstechniken fuer Scher - versuche gegeben, insbesondere fuer die Laborversuche, um so ohne Praezisionseinbusse und mit demselben Aufwand eine groessere Anzahl Versuche in derselben Zeitspanne durch - fuehren zu koennen; andererseits, wurden auch noch die durch die Neigung der Scherflae - che und die Durchfuehrung mehrerer Gleitversuche entlang einer selben Flaeche verursacht en Einfluesse untersucht.

INTRODUCTION

The importance of the shearing and sliding characteristics as regards the safety of large works makes it necessary to determine these characteristics, when ever possible, through in situ and laboratory tests.

As they present more difficulties and require larger preparation times and costs, in situ tests are carried out in reduced number, and they are com plemented by laboratory tests, although the former are more meaningful since they concern larger areas. As a result, a significant number of laboratory tests must be carried out so that values ob tained can be processed by statistical methods thus providing final results that represent the shear characteris tics of the rock mass with a reasonable accuracy.

The following considerations are based on the results of laboratory tests on 55 specimens of weak materials. Out of these, 44 consisted of mudstone and sandstone, 7 of clay, and 4 of clayed schist with unfilled discontinuities. Of the specimens consisting of mudstone and sandstone, 28 had infilled discontinuities and the others 16 had no discontinuities (mudstone-mudstone and mudstone- - sandstone contacts).

Contributing to a better adaptation of the ISRM suggested method for shear tests, to the actual conditions in which they are carried out and that may influence the final results.

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