HPT puts money in the bank
Published 2010-04-22 00:00:00 | Updated 2010-04-26 20:55:36
It costs money to drive a tunnel. Manpower, know-how, heavy equipment, materials… it all adds up. But whatever the project, large or small, straightforward or complex, there are always savings to be made if the right method is used. Atlas Copco calls it HPT (High Precision Tunnelling).
As every tunnelling engineer knows, there are almost as many ways of driving a tunnel as the number of rock formations that exists around the world. Technology has come a long way in the past decade, but even the most proven tunnelling methods often fail to live up to demands, resulting in time-consuming remedial work and extra costs that break budgets along with each new blast.
Insist on total precision
The answer, is simple: insist on the one thing upon which everything else depends: total precision. Quite simply, the closer a tunnel is blasted to match its planned profile, the more you save in terms of less shotcreting, extra rock bolting and other corrective work.
A better quality tunnel is the road to a better overall economy and today Atlas Copco’s HPT concept makes it possible to achieve that goal in every type of tunnelling project.
The concept consists of five advanced technologies, working in harmony with Boomer drill rigs – Tunnel Manager, Rig Remote Access, Total Station Navigation, Tunnel Profiler and Measurement while drilling.
Tunnel Manager is a PC-software that enables the worksite office to provide operational support to Atlas Copco Boomer rigs equipped with the Rig Control System (RCS). The software is used to plan, store and evaluate data for the drilling process, and makes it possible to optimize the tunnelling cycle.
Rig Remote Access (RRA) ensures rapid and secure transfer of the latest data to and from the drill rig – as well as secure data storage. With the drill rig online, the whole organization has constant access to the latest information – the production planning department can initiate immediate analyses of the incoming data. Automatic updates eliminate the need to manually collect new drill plans for the rig operator, and service personnel can conduct online diagnoses and order appropriate replacement parts prior to service calls.
Total Station Navigation (TSN), enables the rig to be rapidly navigated to precisely the right position every time. Navigation is accurate to within 1 cm compared to the more normal 10 cm and takes no more than five minutes compared to the 10–30 minutes for manual methods. With a 2 000 metre long tunnel, savings of about EUR 100 000 can be achieved. Navigation is conducted by the rig operator, using a tripod-mounted Total Station, in combination with prisms mounted on the rig and tunnel walls.
Tunnel Profiler is a 3D scanning system for rapid and high precision tunnel profiling. A section can be scanned immediately prior to drilling each round, requiring very little extra time. The data is processed and the rig operator is informed about any over or underbreak in a matter of minutes. As a result, drill plans can be corrected quickly, which can save up to 5 cm in overbreak. In a tunnel with a 40 m² profile, this can yield savings in overbreak costs of about EUR 125 000 per kilometre (shotcrete and man hours).
Measurement While Drilling (MWD) is a rig option offering rapid acquisition of vital drilling data, such as penetration rate, feed force, rotation speed and more. With Tunnel Manager MWD, the data can also be used to analyze rock hardness, crack zones and other relevant rock mass characteristics. Thorough knowledge of the rock’s characteristics allows the tunnelling process to be adjusted during drilling.
Used together with Atlas Copco's tunnelling rigs and rock bolting rigs, these technologies optimize the tunnelling process right from the start, thereby reducing unnecessary extra work, optimizing tunnel quality and keeping project costs under control.
Atlas Copco developed the RCS system in the mid nineties and have been refining it ever since, in close co-operation with its many customers around the world. That’s why Atlas Copco is the undisputed leader in high precision tunnelling.
According to Konstantin Spinos, Director of Underground Operations at Veidekke, the Scandinavian building contractor and property developer, the HPT concept has helped the company to raise accuracy to levels that were previously unattainable.
“Every tunneller strives for perfection but knows that in reality it is impossible to achieve. The HPT functions developed by Atlas Copco in co-operation with companies like us at Veidekke, help us to get as close as possible to that perfection, whatever the conditions. It makes no sense to spend money on correcting excessive over and underbreak, so by using HPT we optimize our ability to maintain the original tunnel contour and, as a result, also keep our costs to a minimum.”
The system that has been reducing costs since 1998
Atlas Copco introduced its Rig Control System (RCS) – a computerized control system for drill rigs – as early as 1998.
It was an innovation that revolutionized the industry. Since then, the company has led the development in computerized and automated rock drilling. Today, more than a thousand RCS rigs are in operation the world over.
This long experience and ongoing dialogue with customers has resulted in increasingly sophisticated functions, culminating in the concept of High Precision Tunnelling.
A wide range of benefits
Computerized drilling is all about creating more productive conditions for rock excavation. Computerized automation improves drilling rates and drill steel economy. But there are many more benefits such as faster fault detection, lower maintenance costs and enhanced rig availability. A recent study confirms that fully automated drilling will, on average, reduce time at the face by 6 %, increase advanc-e rates per face by 3% and reduce overbreak by 7 cm.
Today’s Atlas Copco rigs feature fourth generation RCS automation. This latest system offers even more refined functions for planning, conducting and analyzing the drilling process, including wireless online data transmission between rig and site office. And it doesn’t stop there. The RCS system and its range of functions is also utilized in many other Atlas Copco products and applications.
Mathias Edhammer is Product Manager, Atlas Copco Rock Drills, Sweden and a key member of the team behind the development of computerized drilling.
For more information contact mathias.edhammer@se.atlascopco.com
Tags: Infrastructure
