Alongside the work of the famous base tunnel Gotthard in Switzerland, part of the proposed railway line Swiss AlpTransit, drilling and blasting of another major tunnel also started this spring: that of Ceneri base tunnel, a length of 15.4 km, located in the canton of Ticino, at the north portal near Camorino, the southern entrance of the cave Vezia and installation through the point of attack of Sigirino. The tunnel consists of two single-track extends south of the base tunnel Gotthard railway line Swiss AlpTransit. Its construction is, like that of St. Gothard, conducted by the company AlpTransit Gotthard AG on behalf of the Government of the Swiss Confederation.
The base tunnel Ceneri should be operational late 2019. Therefore, this tunnel will allow the flow of high-speed trains and heavy freight trains, which did not allow the far mountain slopes of the lines Ceneri.
Digging the tunnel from the main access tunnel (2.3 km long) in the cave began in 2008 and was performed using a computer-controlled tunneling machine (TBM Tunnel Boring Machine) Robbins with a diameter of 9.7 m. The construction site of the two rail tunnels will experience a full activity in fall 2010. Excavation, retaining and coating should be completed in 2016
The consortium Condotte Cossi, which includes the signing of the contract for construction of the tunnel, has carefully considered the offers from different suppliers for machine control, which is lucrative for them. The consortium finally chose Swiss Cat dealer Avesco who was able to provide the majority of machines required for the excavation of the twin tunnels. Avesco, CGT (Italian Cat dealer) and Zeppelin (German Cat dealer) work on the drilling project Ceneri base tunnel. In addition, Avesco already has experience as provided and maintained the machines that were used in the construction of the section Sedrun Base Tunnel the Gotthard, which gives a good advantage. As official supplier to Sandvik, the division "Bautechnik" of Avesco was able to offer a complete range of products including eight drilling jumbos, four underground wheel loaders, excavators eight smaller radius for tunneling, eight hydraulic hammers, eight loaders special, and some equipment for supporting.
The 314D LCR Excavators and Cat 328D LCR, customized by the dealer for tunneling, are rare models in the range of Cat excavators. If the truck chassis and upper structures seem familiar, the shape and size of arrows and buckets are, in turn, special. Both excavators have another characteristic: they each have a dozer blade, heavy duty on the carbody. Covers solid protect the upper cylinder of the blade. This ensures exceptional stability and also allows for grading work. The blade at the back cleans the rock debris present on the crown and on the vertical face of the tunnel while preventing the machine slide rearward. Like all other machines used on the site of tunneling Ceneri, the eight smaller radius excavators are equipped with two fire extinguishers, one located in the cab and the other outside the excavator.
Avesco has invested in many hours of labor to transform a Hydraulic Excavator 314D LCR with a smaller radius in a standard Cat excavator for tunneling of 15.5 tons. What first jumps to the eyes, this is the small size of the main boom. Mechanics removed the original arrows with a length of 4.65 m and welders have made new ultra short arrows, with a length of 2.01 m. Apart from the solid cylinder cover, arm and hydraulic quick coupler is standard. In addition to the forks of the ripping alarming rate, it is possible to fix a hydraulic hammer Sandvik BR2266 of 1330 kg, and a backhoe bucket on the standard for quick loading applications. A FOGS (part of protection against falling objects) has been integrated into the cabin to protect the user.
With a curb weight of 43.5 tons, the Cat 328D LCR model is so far only reduced radius excavator for tunneling of the 40 ton category. The rear swing radius of only 1.90 m slightly exceeds the undercarriage. The 328D LCR incorporates the upper structure of the model 329D and the undercarriage Model 336D L. The arrow with cross sections of torsion-resistant, specially designed for this model, was manufactured by the German dealer Zeppelin Cat. The main boom of the 328D LCR swivels 45 degrees left or right of center. The tilt mechanism provides the excavator maximum operating flexibility in narrow tunnels. The arm of the bucket measures 4.65 m long and can accommodate all types of buckets, hammers and cutters integrals. Avesco provided four hydraulic crushers to Sandvik BR3088 2370 kg for Hydraulic Excavators tunneling Cat 328D LCR.
For the work of loading and offloading in the galleries located close connection between the two single-track tunnels, Avesco amended four Cat 938H Wheel Loaders. To make them more suitable for applications of tunneling, the engineers have shortened the fenders on each side and removed parts of the rear fender. The maximum width of the loader is now 2.6 m. To better protect the user against falling rocks, welders have set a second roof over the cab, and protection of the windshield. A movable cover that prevents the tilt cylinder is damaged and sturdy steel beams on the counterweight protects the radiator side impact. Side dump buckets were manufactured to precise specifications by Ullmann, the Swiss specialist equipment mounting. Like all Cat machines used on this site tunneling, the 938H wheel loader is equipped with an engine with a diesel particulate filter and a sprinkler system "Fogmaker". In an emergency, the user can operate the system manually.
All users have a sticker on the back of their helmet to prove that they have received appropriate training, provided by Avesco, and they are allowed to use the machines mentioned.
When the drilling and blasting at full turn, the team's point of attack through Sigirino dig tunnels simultaneously both north and south. After each blasting, a hydraulic excavator for tunneling 328D LCR sinks inside the tunnel to clear debris from rocks present on the crown and the vertical face and the cut ends with the hydraulic hammer. Once cleaned, the area is secured with anchor bolts, steel mesh and shotcrete before the loader removes the Sandvik underground excavation at the tunnel face and empties into the facility mobile crushing. Debris materials are transported out of the tunnel by a conveyor belt system extensible. Approximately 20% of the excavated rock can be reused for the production of concrete on site. The balance will be the development of the area around the construction site.
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