Robotic solutions for tunneling

More and more sophisticated, current machines have on-board computerized technologies and systems that reduce costs and operator’s interference

Mainly when excavating in hard rock to open tunnels for railways and roads, carry out river diversion for dam construction or extract minerals in underground works, for example, one of the best solutions is still the use of explosives, what demands to drill holes in the rock with five centimeters of diameter and lengths up to six meters, where they are inserted. This is one of the works carried out by drilling jumbos that—in a simplified way—may be described as machines with 9 to 45 tons mounted over crawlers (not much used currently) or wheels and equipped with up to three arms with drills in their ends.

In fact, these machines had a strong evolution during the last years. Currently, they are quite sophisticated machines with on-board technologies and innovations that reduce more and more the interference of the operator. Using computing systems, last-generation sensors and lasers, the jumbos became almost robotic solutions able to be accurately positioned in the drilling fronts to drill the holes in the right places, with the designed direction and depth. And of course these procedures increase the speed of the works and reduce the consumption of explosives and of concrete needed to recover the tunnel walls. Eventually, they reduce the cost of the project.

SUITABILITY

There is always a jumbo that fits better each type or dimension of tunnel. For small tunnels with lower area in the drilling front (such as those of mining and railway, that are high and narrow), models with one or two arms may be used. For largest tunnels (such as those of highways and river diversion, which are as high as wide) larger machines with three arms are the most indicated.

According to Paulo Ribeiro, business manager of underground equipment from Atlas Copco, machines used in mining are more compact to fit the dimensions of the galleries. “The main difference is always the equipment size”, explains him. “Depending on the sections to be drilled, mining jumbos usually work in sections from 3 x 3 to 5 x 5 meters. Construction jumbos may work in much larger sections, according to the type of tunnel to be excavated.”

Another difference is the type of drilling machine that is installed in the jumbo. Construction machines usually have higher power than mining equipment since there are fewer restrictions about power availability. And the commercial director of Machbert, Rui Maximo da Fonseca, remembers another difference. “Construction jumbos require systems to control the amplitude of excavation. These are devices installed to prevent excessive movement of the free rocks and of concrete to be poured on the walls”, explains him.

Among the technical features of drilling jumbos that may establish difference in the operation are on-board automation and computerized systems. “This makes easier the work, with data management and different possibilities of automation allowing the operator to work as a supervisor”, explains Ribeiro. The machine adjusts itself to the operating conditions, reducing costs and optimizing processes.”

Ricardo Binembaum, commercial director of Caimex and dealer of the Peruvian company Rosemin—specialized in the manufacturing of drilling jumbos for mining—in Brazil thinks in a different way. He says that the machines sold by his company work in much more severe environments than those used in construction tunnels. “Models used in construction usually are of larger size and may be completely controlled by computerized systems, since the environments are less aggressive”, says him. “Mines demand simpler and less sophisticated equipment. This is the expertise of Resemin, which has 500 of them working around the world, including in Brazil.”

According to the expert, computerized and automated systems are sometimes a disadvantage in relation to the jumbos used in mining. “Resemin recommends the use of simpler jumbos since the sophistication of electronic equipment installed in machines that operate in severe environments is a limitation to their mechanical availability”, tells him. “Electronic items make them vulnerable when compared to direct hydraulic controls, more simple and reliable in aggressive environments with high temperature and moisture.”