A study on truss bolt mechanism in controlling stability of underground excavation and cutter roof failure

The truss bolt reinforcement system has been used in controlling the stability of underground excavations in severe ground conditions and cutter roof failure in layered rocks especially in coal mines. In spite of good application reports, working mechanism of this system is largely unknown and truss bolts are predominantly designed based on past experience and engineering judgement. In this study, the reinforcing effect of the truss bolt system on an underground excavation in layered rock is studied using non-linear finite element analysis. Different indicators are defined to evaluate the reinforcing effects of the truss bolt system. Using these indicators one can evaluate the effects of a reinforcing system on the deformation, loosened area, failure prevention, horizontal movement of the immediate layer, shear crack propagation and cutter roof failure of underground excavations. Effects of truss bolt on these indicators reveal the working mechanism of the truss bolt system. To illustrate the application of these indicators, a comparative study is conducted between three different truss bolt designs. It is shown that the design parameters of truss bolt systems, including tie-rod span, length, and angle of the bolts can have significant effects on the reinforcing capability of the system

Doers of the word: an enquiry into the nature of action in action learning

A recent trend in public policy in many countries is the requirement for 'joined up thinking' and 'joined up working', including partnership within and between agencies, and between agencies and their publics. This in turn has led to a growth of interest in action learning as a means to bring about the organizational and individual development required for implementing such policies. Action learning, with its emphasis on solving new problems, implementing solutions and learning-to-learn seems to fit the zeitgeist. However, the notion of 'action' in action learning has presented a real difficulty in administering action learning sets in this context. Commencing from a philosophical point of view that emphasises the identity of action and learning, rather than their separation, we report here on three such public sector action learning projects and identify three fundamental features of the action which took place in and around them. Thus: action can occur either inside or outside the set; while it is always an input to the learning process, it can also sometimes be regarded as an output of that process; and finally, the type of knowledge that can be acquired may be in Gilbert Ryle's terms either 'knowledge how' or 'knowledge that'. Five categories of action are identified: expressive action, concerned with feelings and relationships in the set; the enrichment of networks and local knowledge; changes in personal practice; collective action; and organisational change. While organisational change may be regarded as, in one sense, 'the big prize' of action learning, it should not blind us to more subtle processes of learning and change that occur