Infrastructure Engineering - Theses
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ItemGeotechnical studies for machine tunnelling( 1983)An exhaustive program of measurement of the mechanical properties and drillability test indices of rocks from Australian tunnels and mines was followed by extensive statistical analyses, to find correlations between the various rock properties and drillability tests. Significant correlations were found between Young's modulus and point load strength, Young's modulus and shear strength, and shear strength and unconfined compressive strength. Several other relationships between properties which had been previously published by other authors were confirmed but modified, with less significant correlations. Several laboratory drillability tests, which are small-scale simulations of full-size field drilling and tunnelling machines, were shown to give results which were well correlated with groups of rock mechanical properties. In most cases, however, there were no simple correlations, which could unequivocally explain the mode of rock failure. Rock failure in response to a drill or cutter, whether full size or laboratory scale, is evidently a complex and subtle inter-relationship of several factors. The performance of a full-face tunnel boring machine was monitored, and correlated with the results of mechanical property and drillability tests performed upon rock samples taken from the walls of the tunnel. Significant correlations were found which can be used as equations to predict the advance rate of a tunnel boring machine and the rate of wear of the cutters. The significant independent variables include drillability test indices, the machine propel or thrust force, and physical properties of the rocks. Tensile or compressive strengths were not found to be significant factors in predicting tunnelling machine performance.