6 minute read
The new way of survey
by Christian Martin Spannagel, Sales & Marketing Manager at LITEF
Has it always been your dream to hold a device in your hands that shows your exact orientation? Regardless of where you are and when? Unless you happen to be at either of the arctic poles, we can make your dream a reality. Outstanding tasks often drive technology development. At LITEF, we understand this very well. With almost 60 years of experience in the development and manufacturing of safety-critical inertial measurement systems, we are a proud pioneer, introducing new technologies, such as fiber-optic or MEMS-based inertial systems in avionic, marine and defense.
Mining operators and civil construction engineers have long been looking for an easy-to-use surveying instrument. A reliable device, ready to operate anytime, anywhere without additional setups or equipment, simple to operate – yet safe and reliable. Especially in underground operations, it is important that the instruments work independent of environmental influences, such as magnetic disturbance, temperature variations, shock and vibrations.
Now imagine a compact, hand-held device that meets all these requirements. A device that can be used for surveying, monitoring, alignment, adjustment and much more. We took up the challenge and converted one of our safety-proofed inertial measurement systems into a battery-powered North finder gyrocompass. The result: LITEF Portable Alignment Device, LiPAD®-100.
Drive for reliable independence
are provided in real-time. It is designed for one-man operation in small or complex environments. No special skills, additional alignment equipment or survey setup are required. Alignment, built-in test, performance control - everything is done internally.
In your hand, you hold the newest generation of navigational-grade fiber-optic gyroscopes and MEMS accelerometers. Combined, this advanced inertial system allows you continuous measurements - wireless and in real time - in environments where standard equipment is too bulky or GPS-dependent.
The LiPAD®-100 offers Bluetooth® connectivity to communicate with your hand-held device. An Android-based software app (free download in Google Play online store) enables the operator to control the device and view the measurement data in real time. All data can be stored and shared along with the operator reference, project name, date/time, and - if available - GPS information of your current position.
The base plate can be used for repeatable reference measurements as well as for attaching customized fixture mounts. The compact design en-
ables the operator easy handling, even in confined spaces. Two replaceable and rechargeable batteries ensure that you never run out of power. A battery charging device, a storage/transport case and a technical manual are provided with the system.
Uniqueness meets ease-of-use
LiPAD®-100 saves a lot of time on your measurement task. Measurements that normally take hours, are completed in just a few minutes. No wasting time until a surveyor has been contacted and is available on site. Thus, LiPAD®-100 drastically reduces downtimes during surveying tasks. The available personnel (e.g. drill rig operators) can carry out the survey independently, including measurement data storage and reports for evidence.
The success to-date confirms our approach: not long after commencing series production, LiPAD®-100 is now in use worldwide. We have received consistently positive feedback from mines in North America and Sweden, and from construction projects in Austria, Slovakia, Germany and Bhutan on the efficiency of this multi-talent. Moreover, new World map by Joel Wisneski, the Noun Project
applications are constantly being added, about which even we are amazed to learn.
To illustrate what is possible with this measuring device, we have three examples of how it has been applied below:
Example 1: Perform approximately 300 injection drills in the cramped basement of a historical building in Vienna
A new subway line is to be built in Vienna’s city center. The tunnel will pass under a historic building of the University of Vienna, at a corner of the building and a depth of 26 m (85.30 ft). At this point, the building is to be secured by an additional concrete foundation. To construct the foundation, a renowned Austrian specialist civil engineering company was commissioned to drill over 300 boreholes, each 12 m (39.37 ft) long, from the basement of the building. The concrete was pressed through these boreholes into the ground at high pressure, each creating a cylinder with a length of approximately 10 m (32.81 ft) and a diameter of approximately 1.5 m (4.92 ft). The boreholes were drilled down vertically into the ground or at defined azimuth and pitch angles, so that each cylinder could also be created below the existing foundation walls. With LiPAD®-100, the drilling machines could be aligned quickly and with the required accuracy. Due to the limited space in the basement, the compactness of the device was key to continuous operation. This flexibility reduced the construction time from 21 to 15 days. The equipment and personnel were available for the next job six days earlier.
Example 2: Tunnel stabilization at hydroelectric power plant in Bhutan
Due to a collapse in an underground cavern at the Punatsangchhu-2 power plant on the Puna Tsang Chhu river, 18 000 m (59 055 ft) of soil injection and 19 000 m (62 335 ft) of anchors for back-anchoring were needed to stabilize the subsoil. Time was of the essence, so up to five drilling machines had to operate simultaneously, which also led to extremely tight conditions inside the tunnel. The handy LiPAD®-100 could easily be moved between the drill rigs to adjust the drilling direction. Measurements are always made individually without being affected by previous measurement error accumulation. The gyrocompass does not require a direct line-of-sight and the recorded data maintains overview of the large amount of the individually drilled holes.
Example 3: Borehole trajectory measurement at a landfill site
At a landfill site, drainage pipes are laid in the foundation of the landfill. In this particular case, one such pipe was defective and needed to be rehabilitated. For this purpose, a vertical shaft had to be sunk at the position of the damaged area. In order to determine the exact position, the course of the drainage pipe had to be determined from an existing shaft. The distance of the damaged area from the existing shaft along the pipeline was known from a previously performed video survey - 31.4 m (103.02 ft) along the pipeline. The course of the drainage line was determined with a small-sized MEMS memory rate gyro system from Inertial Sensing (isGyro). This tubular probe was pushed in manually with a rod and then pulled out again with a cable. Initial measurements of the heading, pitch and roll of the isGyro were taken during entry and exit with the LiPAD®-100.
The isGyro used measures relative position changes throughout the survey process. The determination of the initial direction with respect to geographic north was carried out with the portable LiPAD®-100 fiber-optic gyrocompass. The combination of these two gyro tools resulted in an accurate trajectory over the complete length of 31.4 m (103.02 ft).
Particularly in mining, small probes are often used for surveying and exploration. In combination with the LiPAD®-100, not only the trajectory but also holes’ absolute orientation may be determined.
Basement drill setup by Claus Kühne from LITEF
Summary
LiPAD®-100 is a compact, easy-to-use gyrocompass that provides accurate north direction, roll and pitch angle in real time to your Android device. Its flexibility is suitable for alignment, surveying and monitoring applications, regardless of environmental conditions. Any operator can conveniently use the measurement device in the field, without necessitating time-consuming survey equipment setups. Especially for drilling work in mining, the battery-powered system works independent of magnetic influences, shock/vibration effects, temperature variation or harsh settings, like dust and mud – a solid companion for all circumstances. C
