|BMVIT Experts||References_264||Road tunnels||Consultancy||Lombardi Reference Page||Lombardi Reference Page |
The Austrian road safety legislation requires formal approval of new tunnels as well as tunnel rehabilitation projects by the ministry of transport, infrastructure and technology.
Approval is required for the basic design (STSG §7) as well as the final design prior to commissioning (STSG §8).
In this regard and on behalf of the ministry, Lombardi SA has been mandated to establish safety expertises regarding the following tunnel objects:
- Tunnel chain Klaus
- Kaisermühlen Tunnel
- Liefering Tunnel
|Agua Negra Tunnel||References_187||Road tunnels||Preliminary studies; Civil designs; Electromechanical designs; Owner's support||Lombardi Reference Page||Lombardi Reference Page |
The Agua Negra tunnel is the main component of the "Bioceanic Corridor", an international project aimed to set an efficient roadway crossing through the Andes Cordillera, connecting Porto Coquimbo (Chile) to Porto Alegre (Brazil).
The project includes the construction of a 13.9 km long twin tunnel, linking the two portals at 4'080 m a.s.l. (Argentina) and 3'605 m a.s.l. (Chile). The tunnel is provided with cross passages every 250 m, two ventilation caverns (one provided with a vertical ventilation shaft of 500 m, the other with a 4.5 km long ventilation tunnel). The project includes also the ramps and the control building. The cross section is horse-shoe shaped and the carriage way is two lane wide, with a free section 7.50 m wide and 4.80 m high. There are walk ways on both sides. According to the concept for a longitudinal ventilation, the tunnel is not provided with an intermediate slab.
The construction concept is to excavate the tunnel from both portals, with two contemporary and independent excavation faces each. The excavation will be drill & blast in order to assure the maximum adaptability to the geological conditions.
Particular aspects of the project are the high elevation of the portals, the distance to the nearest urban center (>200 km), the extreme meteorological conditions in terms of wind and thermal excursion and the high seismic risk.
Lombardi is responsible of the new conceptual study, the preliminary project and the technical tender documentations for the underground and external civil works as well as for the electromechanical equipment.
|New Albula Tunnel II - Lot 105, Consolidation Raibler Cornieule||References_1842||Railway tunnels||Special studies; Construction supervision||Lombardi Reference Page||Lombardi Reference Page |
The 5‘864 m long Albula Tunnel (I) is situated on the railway line Chur-Thusis-St. Moritz and was put into operation in 1903.
The new Albula Tunnel II is being constructed parallel to the existing Albula Tunnel with an axial distance of 30 m. When constructing the first Albula Tunnel I, the aquiferous zone of the so-called Raibler-Formation (cell dolomite rock) already revealed to be a geologically difficult zone. In 2013, starting from a specially excavated cavern connected to the existing tunnel, exploration drillings have been done in the whole Raibler-Formation zone in order to develop a more accurate geological model.
The cavern, situated in the axis of the Albula Tunnel II, is only accessible through a cross passage from the Albula Tunnel I. Following the drillings results, the Raibler-Formation can be subdivided in three different geological sectors. The sector denominated III is a fault zone of silty fine sand (swimming Raibler-Formation) with a water pressure of approximately 5 bar.
For safety reason the sector III will be excavated with the freezing method. Before starting the excavation, the ice casing will have to be built. This will perform a temporary support against rock and groundwater pressure and furthermore ensure the sector’s impermeability during construction time. Apart from the drillings for the construction of the ice casing, control drillings to monitor the ice casing’s impermeability and injection and drainage drillings to reduce the amount of water, will be necessary. The ice casing will be retained until the termination of the excavation and inner lining in sector III.
|Garibaldi Bridge Island La Maddalena||References_3746||Various traffic infrastructures||Civil designs||Lombardi Reference Page||Lombardi Reference Page |
The new Garibaldi Bridge connects the island of La Maddalena to the island of Caprera and was built as part of the extraordinary works planned for the G8 meeting in July 2009, which was later moved to the city of L'Aquila.
The project involves the removal of the temporary Bailey-type bridge and the construction of a new road and pedestrian bridge. The longitudinal profile of the new deck is circular curved, the cross-section and overhangs of the pavement are of constant size while the core has a variable width and thickness.
The bridge extends above the sea along a straight axis for about 52 m, with a maximum height of about 5.6 m above the water level. The cross section of the bridge is 10 m wide, the space dedicated to vehicular traffic is 6 m. On the sides there are two tapered corbels which constitute a protected pedestrian and bicycle space of 1.8 each.
The deck structure is composed of 2 inverted symmetrical arches with an upper slab-chain. In the intermediate section, the connection between the arch and the slab is a system of metal props inclined in a fan shape in longitudinal and transverse direction to form a regular mesh of supports for the slab. The slab is pre-compressed in the longitudinal direction by means of a diffused system of post-tensioning cables composed of compact, non-adherent 0.6" section single-stranded viplate and protected by HDPE sheathing.
Due to the extraordinary requirements imposed by the client, the construction was completed in just 4 months.
|Design of complex tunnel portals||References_4717||Various underground structures||Civil designs; Special studies||Lombardi Reference Page||Lombardi Reference Page |
Advanced numerical analyses of tunnel portals are needed in case of several complex design conditions. Lombardi Ltd. provides studies in this field, using both commercial 2D and 3D numerical software as well as in-house developed softwares. Lombardi has gained specific experience by dealing with design cases of considerable complexity.
A study of particular relevance was the analysis of the portal of three tunnels located within a large slope of cohesionless soil. In this case, the close to limit equilibrium condition of the slope itself, as well as the diagonal entrance direction of the tunnels, called for 3D numerical modelling. The effects of the excavations on the slope stability were evaluated and the tunnel lining was designed, taking into account the staggered excavation start of the tunnels. Additionally, due to the high seismicity of the site area, seismic analyses were performed.
For the design of portal supports, a particular case to be studied was the entrance of a double tube road tunnel through a railway embankment. Because of the diagonal entrance direction of the tunnels, the use of permanent soil anchors in the design of the retaining structure would have interfered with the nearby tube, and was therefore not allowed. Therefore, the final design provided a support structure to withstand the long term earth pressure. The complex portal geometry required 3D numerical modelling. Furthermore, considering the tunnels passing underneath an existing railway line, possible settlements at the railtrack level had to be verified.
|Preliminary design of TBM||References_4931||Various underground structures||Preliminary studies; Special studies||Lombardi Reference Page||Lombardi Reference Page |
The selection of the excavation method is a key aspect for the design of tunnels. The mechanized excavation by means of Tunnel Boring Machines (TBM) is possible and convenient only in specific geomechanical conditions. The preliminary TBM design becomes therefore relevant in order to define the main features of the TBM, determining the feasibility of this methodology, and considering schedules and costs.
The main characteristics of the TBM, i.e. advancement thrust, cutter head torque, shield geometry, cutter head properties and power of the hydraulic equipment, can be established by studying the geological framework and carrying out a proper geomechanical analysis. Other relevant aspects as the drilling machinery for the grouting works and geological investigations as well as the equipment required for the backfilling of the annular void can also be defined at this stage.
In specific geomechanical conditions, advanced calculations (typically 3D) could be required. The performance of such models must take into account the interaction between mechanized excavation and the geological setting.
Lombardi Ltd. has been actively involved in this engineering framework, carrying out successfully the preliminary TBM design regarding multiple underground works: highway, railway and hydraulic tunnels, rocky and soil ground, with high overburden or in urban areas.
|Cumbidanovu dam||References_430||Dams||Civil designs; Construction supervision; Monitoring / Safety / Operation / Maintenance; Owner's support||Lombardi Reference Page||Lombardi Reference Page |
The Cumbidanovu dam is located on the main course of the Cedrino river, about 250 m downstream from the confluence of the Rio Sorasi, in the municipality of Orgosolo, province of Nuoro. The section of the dam is situated in the locality of Cumbidanovu, about 1.5 km linear distance from the center of the town of Orgosolo.
The purpose of the dam is to realize a reservoir with a total capacity of 13.3 hm³ of water for the irrigation of approximately 2’810 hectares of land in the territory of the Municipalities of Orgosolo, Oliena Nuoro, Lula and Dorgali.
The works started in May 2011, but in November 2013, the central-eastern part of Sardinia was hit by an unprecedentedly intense weather event (cyclone “Cleopatra”) with very heavy rainfall affecting in particular the Cedrino catchment area, and the site was inundated by an exceptional flood event that caused extensive damage to the structure and the complete destruction of site facilities.
The services now contracted by the dam operator include the reconstruction of the previously built structures and the design of a 73 m high concrete gravity dam (V=303.297 m3) with an inclined axis with a radius of 330 m, divided into 18 segments of 13 m width plus a 19th segment with a length of 10.50 m and a spillway capable of handling the exceptional flow of 1’200 m3/s.
The project also includes the construction of a bottom outlet in a metal tunnel incorporated in the structure with a maximum flow rate of 165 m3/s and a first section of the future irrigation pipeline, which will also be used as a penstock for a future HPP (not included in the contract) with a capacity of about 700 kW and an average annual production of 1.9 Wh/year during the autumn-winter period.
|ENEL - HPP Los Cóndores||References_5507||Hydroelectric plants||Civil designs; Consultancy; Owner's support; Special studies||Lombardi Reference Page||Lombardi Reference Page |
Los Cóndores is a 150 MW HPP, including a 12 km long headrace tunnel (4.6m diam, excavated by D&B and a DS hard rock TBM), a 120 m high surge shaft (6m diam), a 480 m high pressure shaft (2.6m diam), both being excavated using a raise borer machine RBM, and a 1.6 km long subhorizontal pressure tunnel leading to an underground powerhouse accommodating 2 Pelton units. The region is volcanic, with several active volcanoes in the recent geological eras. Maule Laguna volcanic complex is one of the major and the geological formation are essentially dacitic and rhyolitic lava field with rich tuff and volcanic breccia presence in subhorizonal sedimentation and several lava and basalt domes and dikes crossing these formations. Excavation of the upper waterway (HRT) is foreseen in two phases through a central adit by TBM, in order to shorten the time for accessing and execute the vertical works. During the excavation of the HRT lower reach, the TBM got stuck in a cohesionless material, likely the seat of a paleo-basin (syncline) or a paleo-canal within the lava and breccia banks. The services targeted the understanding of the situation, definition of the operations required for the TBM to be safely unlocked from the jammed conditions and option for realizing a bypass around the TBM in case no success was provided by other means. Because of the significant modification of the working program, the evaluation was required of the options for realizing the upper reach of the HRT by other mechanized means (second TBM) or other excavation method, given the logistic conditions at site. Possible optimization of vertical works, in terms of efficiency and realization concept was also part of the required services; in particular, a preliminary study considering 5 alternatives of the scheme combined with different excavation methods options (D&B and/or RBM) were carried out, in order to analyze the possibility to disassociate the construction of the vertical works from the TBM advance and to better manage the geological and construction risks associated with vertical works construction.