Construction World April 2017

GEOTECHNICAL ENGINEERING

A CONNECTED APPROACH: the application of LiDAR in construction

The African mining industry is starting to experience growth after a prolonged period of negativity, thanks to conditions in China now stablising and rising commodity prices. But while this recovery is welcome, growth is expected to be sluggish. Here, Matthew Bester, general manager, Africa from geospatial technology specialist 3D Laser Mapping explains how technology can be used to streamline operations so firms can retain profit levels.

use of LiDAR increases the accuracy of a scan because the light moves at a constant and measurable speed, enabling operators to calculate distances more efficiently. The ability to collect time-series measurements remotely also means that land changes can be detected and patterns of behaviour identified, enabling pre-emptive work to be carried out before problems occur. When combined with an integrated GNSS system and an Inertial Measurement Unit (IMU), a record of the precise global location and spatial position can be added to the data from the laser scanner, resulting in a 3D point cloud. From this, a digital terrain model (DTM) can be created, providing a detailed picture of the environment, including millimetre accurate visualisations, which can then be used to calculate slopes and gradients, widths and depths and clearances for machinery and vehicles. Advances Recent advances in LiDAR systems have made them more mobile, compact and affordable, so they can be used on construction projects of any size. Previous devices, like terrestrial laser scanners, require operators to undertake numerous set ups to generate a meaningful DTM. Not only is this time-consuming, it makes it all the more difficult to access those hard-to- reach or dangerous locations. This is where mobile LiDAR technology can be a real asset to surveyors and project managers: by mud has done its job, it then fills any void space due to over-cut. On large and longer bores, it is common practice, although not essential, to use recycling units, says Carnicelli. “This is due to the large volumes of bentonite required for the size of the bore, and is achieved by creating a sump hole in the ground into which the returning mud can flow,” he says. “From there it is then pumped to the recycling unit and the mud is cleaned through a process of shakers and cyclones. After all the debris is removed, clean mud is mixed with a small amount of bentonite to ensure the continuity of the viscosity, and can then be pumped back down the bore hole.” 

Automation technology Automation technology is used widely in manufacturing and construction but the development of specialist applications means demand for it is growing in mining. Using connected, networked tools and machinery enables operators to access data about the site which can increase efficiency and reduce the need for workers to access unsafe areas. With scaled-down operations winding back up, companies can now look to data-driven methodologies as a way to improve their processes and employ new team members who can use technology for positive change. LiDAR systems A recent development in this field is LiDAR (Light Detection and Ranging) systems, which use lasers to build in-depth, three- dimensional models of a site so they can be accurately monitored, without people being exposed to dangerous situations. While remote surveying tools such as total stations, are not new in a mining setting, the and location of the drill head when it is in the ground. Data on both the depth and the pitch of the drill-head is available to the operator and tracker on surface at the push of a button. The unit also has its own mixing plant, for creating the ‘mud’ of bentonite and water which is the ‘blood flow’ of HDD, providing coolant to the drill head and reamers, stabilising the hole by lining the walls, and flushing the hole clean by carrying out the heavy debris being cut. At the final stage of the project, when the product pipe is to be inserted, the mud plays another important role: lubricating and suspending the pipe, and thereby protecting it on its journey down the hole. When the

After a protracted slump, signs that the African mining industry is starting to recover are emerging. In the last quarter of 2016, the price of copper increased by 10%, compared to the same period in 2015. During this time, the price of iron ore also doubled, helping metal and mining corporation Rio Tinto finally return to profit following losses of USD866-million in 2015. This growth is being fueled by demand and investment from the Asian continent and despite upturns in certain areas key to stabilising the African market, the industry remains volatile, with Rio Tinto also reporting slumps in the copper and diamond product groups for the last 12 months. To ensure businesses are robust enough to withstand these fluctuations, mining operators will no doubt look to reduce capital expenditure through technology. Part of this involves looking to other sectors to see how they have recovered from a crisis, while addressing issues like labour costs, more rigorous safety regulations and skills shortages. infrastructure or buildings on surface. The competitive advantage Among the various applications in which HDD offers a competitive advantage, he predicts that desalination plants like the one at Port Alfred are likely to present substantial opportunities for this technology in the near future, as these plants become an increasingly popular option for coastal towns affected by regular droughts. The ability to govern the direction of the drill head is vital to the versatility of the rig, allowing a bore plan to be designed and accurately implemented by the highly- trained operator. Moreover, the operator and tracker can at any time check the depth

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CONSTRUCTION WORLD APRIL 2017