NATM

The constructed tunnel is part of the City Trunk Line project in L.A. (replacement of an existing water trunk line). The tunnel is located at the junction of Riverside Drive and Whitsett Avenue. It is between eight and ten feet in diameter and has a total length of 252 feet. To fit between the existing structures in the ground (foundation piles of a bridge), the tunnel follows an S-shape and is divided into sections with different geometries. The tunnel was built using NATM/SEM construction methods. The primary support measures included fibre reinforced shotcrete, lattice girders and spiles (rebar spiles and grouted pipe spiles).

The Brenner Base Tunnel (BBT) is a 64km long railway tunnel connecting Austria and Italy. Once completed, it will be the world's longest rail link underground. In addition to the two main tubes, the project comprises a complex set up of exploration adits, crosscuts, emergency stops and additional access tunnels, excavated by TBM and SCL methods. Dr. Sauer & Partners provided tender support services for the 18km lot H51 Pfons-Brenner and was responsible for creating the bid documents as well as conducting QA/QC services. The documents covered issues such as TBM choice, annular gap filling, reuse of excavated rock, rail delivery of construction materials, construction logistics and pre-excavation grouting.

University Link is a 5km light rail extension that runs in twin-bored tunnels from Downtown Seattle north to the University of Washington, with stations at Capitol Hill and on the University of Washington campus. The project further includes 20 cross passages located in soft ground and a maximum design water head of 60m. To deal with the prevailing geological conditions, specific ground support categories were developed. Steel fibre reinforced initial lining, sheet membrane waterproofing and CIP final lining were utilised.

University Link is a 5km light rail extension that runs in twin-bored tunnels from Downtown Seattle north to the University of Washington, with stations at Capitol Hill and on the University of Washington campus. The twin-bored tunnels are connected with 20 cross passages. Dr. Sauer & Partners performed the temporary and final support design for the cross passages. This included the design of excavation and support measures and the development of specific ground support categories, settlement analyses, and the structural analyses of initial and permanent lining.

Crossrail is a 118km railway line along an east-west route across London. Its central section runs via 21km twin-bore tunnels connecting eight underground stations and represents one of the world's largest infrastructure projects. Dr. Sauer & Partners was assigned to provide Category III independent design checking services on the Sprayed Concrete Lining works for the complete Whitechapel and Fisher Street SCL structures. Additional 3D non-linear FEA and assessments were carried out for the wraparound and junction structures of the Liverpool St Station and the Bond St Station.

A major collapse during construction of the Thierre Tunnel in 2009 led government officials to call on NATM experts to come up with an innovative fix for the 5.6km, two-lane twin tunnel, which is part of the new Reshen Kalimash Motorway. Recommended stabilisation measures by the Dr. Sauer/iC JV such as backfilling, ribs and fibre shotcrete were implemented and halted creep movements. An alternative design was developed and replaced the original horseshoe profile by an ovoid shape. Pre-treatment, excavation works and support installation were accompanied by extensive monitoring.

The City of Edmonton built a 3.3km Light Rail Train extension from Churchill Station to the Northern Alberta Institute of Technology. Approximately 670m of the extension are underground consisting of ca. 430m of twin tunnels of 6m nominal diameter. NATM/SEM tunneling was applied. The software 2DOC, which was at that point used in North America for the first time, allowed real-time tracking of all geotechnical instruments on the project, as well as the recording of the actual geotechnical conditions and the grout support elements installed.

Silver Line Phase III is an underground extension of the Silver Line from the current terminal at South Station into Downtown Boston. The tunnels through Boston's Chinatown lie up to 25m below surface and include ca. 1400m long-running tunnels, two stations and complex underground junctions. The NATM design alternatives for LRT / Busway tunnels are located beneath existing subway stations and running tunnels. 3D modelling tools were utilised to create multiple alignments.