TCAD+ system provides advancing drilling accuracy and blast economy

TCAD+ was originally developed as an 'aiming tool' to achieve improved accuracy based on pre-designed drilling plans in combination with more automated drilling. It therefore works with Sandvik iSURE software for drill pattern and blast design according to the planned tunnel dimensions of excavation. In addition to accuracy and easier directional control, many other benefits have resulted from the development work. This means that Sandvik drill-rigs fitted with the new TCAD+ (Tunnel Computer Aided Drilling Plus) are able to offer customers highly accurate drilling with a resultant range of savings and higher efficiencies achievable.

What's new
Not only is blasthole pattern accuracy improved by TCAD+, the same accuracy can now be applied to rockbolt pattern formation with full monitoring on the new operator display console. The system is also applicable to long-hole (probe and grout) drilling, since TCAD+ makes it easier to add to the number of drill-rods used without monitoring complications. There is now a wider range of navigation options rather than just a laser beam. The range now includes the use of a tripod-mounted total station to provide the reference. One of the benefits is that it enables operators to carry out routine check measurements and adjustments once the total station has been set up by the project surveyor.

A new, larger (12-in. - 305-mm) touch-screen, high-contrast, color display is a major feature of TCAD+, and also available for other forms of Sandvik drill-rig instrumentation. It facilitates many advantages for operators. Not only does it provide more information, it does so with what is described as a 'state-of-the-art' Graphical User Interface (GUI) with a graphic design and color palette intensively tested and field-trialed for the clearest understanding and adjustment of data as required including easier targeting of the boom. Content is offered on a logical and clear menu-driven format for easy decision-making and understanding covering all functions for navigation, operational monitoring, service logs, faultfinding and maintenance.

iSURE's role
TCAD+ drill-rig control and iSURE tunnel excavation design software work together, closely integrated, for optimum operation in applicable Sandvik drilling rigs. iSURE combines data for the tunnel line, theoretical profile required, drill plan design and analysis of data collected. It also has fast and effective edit and copy functions. Although the previous TCAD control system was compatible with iSURE, the new version has actually been designed for it to ensure complete integration. Unlike similar design software iSURE's principle of drill-and-blast planning uses the most critical point of the round, the back of the round, as the basis for the whole planning process of the round drill plan and charging. Thus the hole-bottom spacing and the burdens are adjusted accordingly, the charges defined and blast-induced rock cracking examined. In this way iSURE defines the optimum accuracy for the round to be carried out by a TCAD+-controlled jumbo and achieve considerable cost savings.

Blasting basics
Sandvik Construction's area manager for tunneling drill-rigs, Juha Kukkonen explains how iSURE fits in with the basic principles of blast design. "The drill pattern is based on burden calculations starting from the contour, i.e. the outermost, row of drill-holes. Design of hole charging depends on the explosive used and its characteristics. The data (parameters) required for blast design are the degree of charging (for different types of explosive), hole spacing (for a selected element of the drill pattern), the burden to the next row, and specific charging (mass of explosive per unit volume of rock). The blast designer will follow the specific charging values required according to the expected rock type and conditions, and for the different elements of the drill pattern. Then the iSURE software takes over to calculate the optimum place for the next row of holes."

Accuracy
Use of a tripod-mounted total station instrument sited at the end of the tunnel drive provides a more accurate reference for rig guidance. Once the total station has been set up and prisms mounted on the drill-rig carrier have been measured, all further measurements are effectively accomplished by the operator with the same degree of accuracy of a few millimeters based on the drill pattern predesigned using iSURE software within the worksite co-ordinate grid. Traditional laser navigation is also supported if required. Simo Sanerma explains, "The position and direction of this laser beam must be known, either within the worksite co-ordinate system or the drill plan co-ordinate grid. By mounting laser targets to the feed-rail of a boom and aligning these targets with the laser beam, TCAD+ can calculate where the booms are located in the drill plan system."

Drilling monitoring
A record of drilling performance is collected for processing by iSure and also during operation using MWD (Measurement While Drilling) sensors. Once drilling is in progress the new display screen offers an indication for the drilling status of the drill on each boom. Standard data collected for analysis includes the geometrical positions of the drilled holes, rate of drilling penetration and other standard MWD values including percussion pressure, feed pressure, rotation speed and incoming hole flushing water pressure. TCAD+ is based on iSURE capabilities for which DTi produces more data and a wider range of reported data types.

Keeping running
Minimizing downtime is a major factor in increasing overall rig efficiency and, consequently, project progress. With TCAD+ the operator and service technician is provided with fully explained built-in alarm systems and a clear, menu-driven display to identify the fault, or faults, and their seriousness. Output of error and service logs for off-site analysis (via USB memory stick) provide technicians, supervisors and engineers with valuable data for analysis of any recurrent problems for rectifications and better planning of future working procedures.

Intelligent models
The new features of TCAD+ and iSure intelligent tunnel drilling can be applied to many existing models through retrofitting the 'bolt-on' components, but perhaps find their best application in new models. The first of the new series of Sandvik DT drill jumbos with TCAD+ capability is the DT821-SC. This can work with the iSure tunneling process control system. The rig is a 2-boom electrohydraulic jumbo carrying RD525 rock drills. In practice iSure with TCAD+ provides for more accurate excavation accuracy, and decreased blasting vibration through optimum hole charging and blast sequencing. This all adds to environmental security during construction and the potential for increased project profitability.

Savings in practice
Actual savings possible obviously depends on the specific site conditions but, based on field experience, Sandvik Construction has developed realistic examples. An estimated 5% better pull is achieved when using iSure with a jumbo using advanced drilling instrumentation. This is equivalent to 12 less excavation rounds in any kilometer of tunnel, with all the consequent savings in time, energy, explosives, etc. As regards profile accuracy, if we take a tunnel section of 8.00 x 8.57m and an estimated 150mm less overbreak, this is equivalent to 4350m³ less rock excavation in one kilometer of tunnel. This results in further substantial savings through reduced spoil haulage.

Another valuable option
In summary, drilling jumbos fitted with TCAD+ 'bolt-on' instrumentation provide a valuable option between more conventional manually operated drill-rigs and the fully computerized iSeries Sandvik drilling rigs with automatic boom positioning. TCAD+ is available as new of the DT series of tunneling jumbos (DT 611-C, DT 821-C, DT 821-SC, DT 1131-C and DT 1131-SC) as well as the DD series intended for mining applications. It can also be retrofitted to other models for which Sandvik will consult on feasibility and practicality of applications.
Summary of benefits and features

• More accurate drilling is achievable, including navigation with a total station rather than a simple laser reference, with no need for painting targets on the tunnel face
• Lower energy consumption, due to better accuracy and minimized overbreak
• Component reliability increased through less inadvertent 'abuse'
• Inclusion of rockbolt hole and long-hole (grouting and probing with easier drill-rod addition) drilling control in the same system using different drill plans, as shown on the operator display
• Much clearer touch-screen operator interface for easier operation (with more than one operator if necessary), fault-finding and troubleshooting diagnostics, resulting in less fatigue and faster control likely.
• Automatic halting of drilling at the correct hole depth frees the operator to start other drilling, letting the system handle the rest
• Boom compensation models as used on the Sandvik i-series drilling rigs
• Improved safety, due to higher tunnel quality with less need for scaling, better support, etc.

Further information please contact:

Katri Miss
Marketing Communication Manager
Surface Drilling and Tunneling
Sandvik Construction
Office Phone: +358 205 44 121
Mobile Phone: +358 50 360 9969
E-mail: katri.miss@sandvik.com

Related products: TCAD+