Tests for assessment of cuttability for boom type tunnelling machines are reviewed with examples of their application. There is a need for recommended methods of determining cuttability on an international scale. It is hoped that this paper would form a basis for reconvening the ISRM Commission on Rock Boreability, cuttability and Drillability during the next presidency of the ISRM.
Dans cet article nous considerons des tests d"evaluation de la faculte de couper des machines a attaque ponctuelle et nous donnons des exemples d"applications. Il est necessaire de mettre en place des methodes qui permettrons d"evaluer la faculte de couper et ce dans une echelle internationale. On props ici une base pour rassembler la Commission SIMR des Facultes de Percer, de Couper et de Forer la Roche la prochaine presidence de la SIMR.
Testmethoden fur die Abschatzung der Schnittleistung von Teilschnitt-Streckenvortriebsmaschinen werden gepruft und Beispiele fur ihre Anwendung werden angegeben. Der Bedarf empfohlener Methoden fur die Bestimmung der Schnittleistung an einem Internationalen Ausmasse ist berucksichtigt. Man hofft, das dieser Bericht die Grundlage fur die Widereinberufung der ISRM Kommission fur "Bohrbarkeit" und Schnittleistung wahrend der nachsten Prasidentschaft der ISRM bilden wird.
Drag tool equipped boom tunnelling machines are a viable and often overlooked alternative to traditional methods for construction of tunnels and underground structures. Though a wide range of rock conditions can be successfully excavated by this type of machine, the numerous configurations, size and power available from a variety of manufacturers make choosing and specifying a machine difficult, unless a logical system is followed.
The paper outlines the components of such a system which involves the evaluation of parameters associated with the ground and the machine.
The factors influencing boom tunnelling machine performance are given in Table 1. Though of great importance it is the total system that has to be considered to obtain realistic performance estimates. In colliery operations development headings have at times taken second place to coal production in terms of conveying debris clearance capacity, leading to poor advance rates. Incentive schemes and restrictions on shift patterns and working practices have a major bearing on overall machine performances.
The paper will concentrate on aspects of performance relating to the ground to tunnelled through and the machine characteristics that have a bearing on tunnel advance rates.
(Table in full paper)
The main factors contributing to machine performance are the intact cutting properties of the rock materials to be excavated and the influence of rock mass properties.
Most of the cuttability tests proposed throughout the world are laboratory tests that rank the rock in terms of its ease of excavation by drag tools. Many imitate, the cutting action of a drag pick.
It is generally agreed that for cuttability assessment for drag tools some measure of strength, abrasivity and cuttability is required. The methods selected have to be standardized, repeatable, simple with ease of preparation and capable of being conducted on borehole core samples.