Tesalia Tunnel, the new landmark on the Coffee Axis in Colombia

July 2, 2021

Underground Rock Excavation Colombia Local Customer story Tunneling 2021

The longest vehicle tunnel on the Coffee Axis will come into service for Colombian citizens in a few months. The Tesalia Tunnel forms part of the Pacific Three Connection project. The Tunnel project is part of the roadwork for the fourth-generation highways that will connect the port of Buenaventura with the center of the country, primarily with the city of Medellin.
At a length of 3,493 meters with a parallel emergency passageway, the tunnel creates a bi-directional connection between the Risaralda Valley and sector 41 on the road to Manizales. The design includes plans for a future tunnel to complete the divided highway. The area of the main tunneling is 130 square meters, and of the emergency passageway, 22 square meters. Excavation has concluded and lining work is now underway, with the tunnel projected to come into service in the second half of 2021.

Excavation challenges

The Tesalia Tunnel has been excavated with the drill- and blast method using two jumbo Boomer E2 drill rigs from Epiroc.

"The two automated rigs equipped with the ABC Regular and ABC Total system ensured we could handle excavation, resulting in less material left behind which minimized operation time and securing the perimeter of the tunnel."

Diego Alexis Ordóñez Rincón , Tunnel manager for the Pacific Three Concession Consortium

According to engineer Ordóñez, R32 bits were used to initiate drilling, and switched to SR35 bits for the rock mass. This increased the number of linear meters drilled and prevented the drilling rod from breaking at the tip, its weakest point.

 

“After analyzing the causes of the break, the soil mechanics of the rock,and the rig calibration, SR35 bits were chosen to minimize breakage and optimize our drilling costs”, he points out.

 

Ordoñez emphasizes the use of 45- and 51-millimeter diameter drill bits, along with the lining systems used for buttressing, which facilitated the work. 525 thousand linear meters of underground rock were excavated using diameters of 45 and 51 millimeters. In drilling and anchoring to rock, 96 thousand linear meters were executed using diameters of 25 and 22 millimeters.

 

Likewise, in drilling for destructive probes, using the Measure While Drilling (MWD) system 8,900 linear meters, and in drainage drilling 3,300 linear meters, were accomplished. For drilling with injection pressure 26,000 linear meters, and for forepoling installation 19,800 linear meters, were executed. A total of 621 thousand linear meters of face drilling, and 58 thousand linear meters of long drill holes were accomplished.

 

For the bracing of tunneling, two MEYCO ME5 shotcreting sprayers were used. The MEYCO ME5 were also used to apply regulating or shaping concrete to smooth surfaces prior to the sealing process. A total of 38,500 cubic meters were shotcreted.

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Epiroc´s all-round service

"During planning of the project various factors determined the technology to use for tunnel boring, like the need for real-time information, the precision needed for drilling work, and the systematization of the tasks. It was also important to carry out work with speed and the versatility to work in two tunnels at the same time, which presented some extreme conditions."

Engineer Gustavo López Correa , Tunnels manager Pacific Three Construction Consortium

“For selection of equipment, we assessed brands that supplied jumbos and robots, offers were submitted to a detailed technical analysis and after considering performance characteristics and added value offers, the project’s managerial counsel decided on Epiroc", he explained.

 

The selection focused on reputable rigs that are reliable and have technical support, along with both sale offers and value propositions, as well as training of operating and professional personnel, thereby achieving better machine and drill-bit performance thanks to the monitoring of operation and Epiroc’s permanent technical support.

 

The CARE contracts entered upon purchasing the rigs included scheduled maintenance at fixed and flexible monthly fees in accordance with drilling hours and qualified personnel for timely maintenance of the rigs. The final agreement also included consignment contracts for drill bits and service for the management, sharpening and consignment of replacement parts for construction equipment.

 

“We managed to keep the new rigs fine-tuned and operational at a high level of reliability. It wasn’t easy to reach this level of service, but we did it by coordinating Epiroc’s technical assistance, the running of the project, and the consortium’s entire mechanical area,” he added.

Training and technical support

In addition to all the technology available in the jumbo Boomer E2 rigs, the work force underscores the training and technical support provided by Epiroc as keys to their successful service.

"Operator training was very important because these rigs have been little used in Colombia. Epiroc provided training modules and a simulation booth to train specialized operators by recreating the different types of situations they can face in excavation. They learned how to make the most of the rigs and reduce damage and operating times."

Engineer Carlos Mauricio Torres Mosquera , Equipment Manager of the Pacific Three Construction Consortium

The engineers who participated in the tunneling emphasize Epiroc’s training and technical support as fundamental to meeting deadlines and drilling costs. “The training was very important because we were able to identify the abilities and skills of our operators and fully exploit the capacity of the drill steel", explains engineer Diego Alexis Ordóñez Rincón.

 

At the same time, on-site bit sharpening service allowed their service life to be extended, thereby avoiding re-drilling while looking after the tungsten of the drilling rigs. “The cost-benefit ratio of the bits supplied by Epiroc was very good for us because the performance we obtained was higher than expected and resulted in lower costs", added engineer Ordoñez.

 

He emphasizes the controls and measuring implemented at the site, which were based on correctly check bearing the drill steel so that the on-site operators could log all activity and linear meters drilled in each shift. "That’s how we determined the exact linear meters at which to do the sharpening and prevent re-drilling with those drill steels. This was essential to obtaining the projected performance", he assures.

The best cost-benefit ratio

When the Consortium engineers were planning the tunnel, they came across a wonderful tool for reaching all their excavation goals in the ABC Regular and ABC Total system.

 

After incorporating blue prints and coordinates, the jumbo Boomer E2 rigs began tunneling at each construction gateway in order to meet at the “cale”, as the junction of excavations is called, in February 2020.

 

The engineer Gustavo Adolfo López Correa summarizes Epiroc’s main contributions to this project with regard to all the technology supplied with the rigs and the opportune technical support provided. “Today the fleet is in very good shape because of the care and investments made during their service. I would think the rigs could easily be sold because they are so versatile, compact, and in good condition. The investment could bring a return because the machines can be sold", he concludes.

A project to the benefit of Colombians

Engineer Aída Amaya Miranda, Manager at the Pacific Three Construction Consortium, highlights how the project has benefited the country’s economy, but in particular the respect for communities, the contribution to the region’s employment, and the awareness of sustainability that has pushed the project forward.

"Pacific Three is a major project that connects with the highways of Pacific One and Two to facilitate cargo transport between Buenaventura and Antioquia. It is a fourth-generation concession whose object is the design, construction, rehabilitation and improvement of the road between La Pintada and La Virginia. It is 146 kilometers of road, of which we will improve 110 kilometers and build 30 kilometers of new road and two tunnels."

Engineer Aída Amaya Miranda , Manager at the Pacific Three Consortium

Construction of the project has directly created about 10,000 jobs. There are currently about 3,000 employees, 60 percent of which are from the area.

 

After five years of construction and now less than a year from handing over the entire project, its environmental management fills her with pride. “We have minimized the environmental impact generated, without the environmental authority having to impose any requirement", she adds.

 

As to the tunneling, she highlights the two built for the Concession: The Tesalia Tunnel and the Irra Tunnel, 420 meters long and already in service.

"We used the latest generation technology with automation features that allowed us to move forward in an adequate manner and within the stipulated timeframe. It was important to have chosen equipment from a recognized brand with a very good track record. Epiroc's technology contributed to the fact that we currently have two tunnels completely finished in their excavation, which has been a very important contribution to successfully complete the works. "

Engineer Aída Amaya Miranda , concludes.
Epiroc operated under the trademark ”Atlas Copco” prior to January 1, 2018.