Cardu, M., & Seccatore, J. (2016). Quantifying the difficulty of tunnelling by drilling and blasting. Tunn. Undergr. Space Technol., 60, 178–182.
Abstract: This study deals with industrial trends in tunnelling by drill and blast (D&B). We perform a statistical analysis of accumulated experience from the 1950s to the modern day to provide advice for proper project management in tunnel driving. The basis of the study is a wide database of tunnel blast schemes. This database is made of excavation parameters, and considers two main families of blasts: with parallel hole cuts and with inclined hole cuts. Such parameters are analysed by means of statistical regression. Correlations are shown. We present a general curve of correlation between tunnel sections and specific drilling and specific explosive consumption. We show how pull efficiency cannot be correlated to a single parameter, and how tunnelling by D&B needs to be treated as a complex system. Finally, we propose a method for quantifying and classifying the difficulty of tunnelling. The deviation of specific drilling (SD) from industrial average trend is used as an indicator of difficulty: easier when SD is lower than average, and more difficult when SD is higher than average. We show how such deviation can be preliminarily associated with lithotypes. This provides to designers and cost estimators a tool of a first approximation for D&B cost prediction at the pre-feasability and feasibility stages of a tunnelling project. (C) 2016 Elsevier Ltd. All rights reserved.
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Cardu, M., Godio, A., Oggeri, C., & Seccatore, J. (2022). The influence of rock mass fracturing on splitting and contour blasts. Geomech. Geoengin., 17(3), 822–833.
Abstract: Splitting and contour blasting are aimed to achieve suitable profiles by cutting along a surface, while common blasting is intended to detach and to fragment relevant rock volumes by increasing the fracturing state. These techniques are adopted in both underground works (tunnels, caverns, quarries) and also for surface excavations (quarries, mines, rock slopes engineering). Contour blasts are widely used techniques in mining and civil engineering to enhance performance while maintaining the safety of personnel and infrastructure. Splitting blasts are mainly used in dimension stone mining to obtain intact blocks of valuable ornamental stone. The parameters of controlled blasting (geometry, charge, blast agent) require an accurate selection using optimised blasting patterns and explosive properties; most of the proposed methods are limited and unsatisfactory due to insufficient consideration of rock mass properties. A quick but effective comparison and analysis of the different characteristics of the rock mass and its heterogeneities is presented, as it indicates a better strategy to determine a tailored blasting design for a given site, thus significantly improving the contour blasting quality.
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Godio, A., & Seccatore, J. (2019). Measuring the Reduction of the Confinement along the Evolution of a Burn Cut. Appl. Sci.-Basel, 9(23), 17 pp.
Abstract: We provide an analysis of a tunnel opening cut in a tunnel face. In particular, we focus on the effect of a “burn cut,” which is a typical parallel hole cut. As the evolution of the opening consists of an increase in the volume of the cut prism and the consequent reduction of confinement of the holes along the initiation sequence, we analyze such an evolution using photographic documentation, as well as evaluating the reduction of confinement by measuring the energy transferred from the explosive charge to the rock mass. The energy was estimated by monitoring and analyzing the vibrations induced by the blasting at three different points. We adopted low-cost shock sensors for monitoring the effect of the detonation times at short distance from the blast (about 10 m). The results show an evident reduction of the shock transfer to the rock mass (i.e., a reduction of confinement) with the increase of the cavity opening. Nevertheless, when only the response of the piezometric sensors was considered, a disparity in behavior among the sensors was noted. On the other hand, when the sensor response was integrated over time, the behavior of all sensors normalized, showing the need to focus both on the oscillation and the duration to properly address the shock effect.
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Silva, J. D., Amaya, J. G., & Basso, F. (2017). Development of a predictive model of fragmentation using drilling and blasting data in open pit mining. J. S. Afr. Inst. Min. Metall., 117(11), 1089–1094.
Abstract: This article presents predictive statistical models for fragmentation in open pit mines using drill-and-blast data. The main contribution of this work is the proposing of statistical models to determine the correlations between operational data and fragmentation. The practical use of these models allows the drill-and-blast parameters, i.e. burden, spacing, explosive, among others, to be optimized in order to obtain a more efficient size distribution.
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