3.4 Drill steel 38 6.3 Flushing of drill cuttings 75 3.5 Couplings 40 6.4 Cutting tools 75 3.6 Drill bits 41 References 76 3.7 Calculation of the necessary drilling accessories 43 7 SPECIAL DRILLING METHODS AND 3.8 Care and maintenance of the bits 43 MOUNTING SYSTEMS 77 3.9 Care and maintenance of drill steel 47 7.1 Introduction 77 explosives / blasting industry of over 100 years of practical blasting experience in most blasting environments. If required, the course can be run for a small group from one organisation at a mine site or at a training venue convenient to the workplace. TRAINING AND ASSESSMENT METHODS The Support Shotfirer and Shotfirer courses involve a theory Drill and Blast From: Encyclopedia of Energy, 2004 Download as PDF About this page Numerical models in geotechnics including soil-structure interaction Ganga Kasi V. Prakhya, Subhamoy Bhattacharya, in Modeling in Geotechnical Engineering, 2021 Deep underground tunnels This example shows interconnected underground tunnels in deep ground in Fig. 8. 2.2 Drill and Blast This tunnelling method involves the use of explosives. Drilling rigs are used to bore blast holes on the proposed tunnel surface to a designated depth for blasting. Explosives and timed detonators are then placed in the blast holes. Once blasting is carried out, waste rocks and soils are transported out of the The hardness, toughness and strength of the rock to be drilled determine the requirements for the drilling tools. In drill and blast tunnelling, clearance of the muck lies on the critical path, which means that each minute saved here shortens the round cycle and thus the overall construction time. Rotary Air Blast (RAB) Rotary Air Blast (RAB) • Cheapest • Least penetrative (~100m) • Geochemical sampling to base of regolith ( ie only penetrates weathered cover over fresh rocks) • Uses compressed air to break ground • Air pumped down through drill rod • Cuttings blown up hole between rod and hole wall • Single barrel technique High-performance drill and blast methods for tunnel construction require that each of the individual working elements that constitute the construction process are optimized and considered as a system of sequential and parallel activities. The advantage of integrating the logistic backup systems facilitates an increase in performance. To achieve increased production, it is necessary to improve The various types of drilling may be classified according to the hole-making action and the hole cleaning method. Those of relevance to NTGS are described below. Open hole rotary drilling is widely used in petroleum and minerals exploration. It uses a slowly rotating (typically <100 rpm) Costs versus excavation lenght for TBM and Drill & Blast methods. As a rule, for excavation lengths longer than 4.5 km a TBM is often recommended, while for lengths not exceeding 1.5 km, the Drill & Blast technique is usually the go-to. Bear in mind that this rule is not set in stone, and you may very well come across a 5 km tunnel being The empirical method continues to be the most common way to calculate the design parameters. Nevertheless, an integration of empirical method, computer modeling and 10 Relationship of sub drilling with blast hole diameter for large blast hole 44 11 List of burden and spacing values for various compressive rock strengths and explosives. 45 - 0 - Controlled detonation drill-and-blast tunneling method was used for 4,300 feet of hard rock consisting p