Projects of underground construction

The staff of Moscow Metrostroy successfully completed drivage of the tunnel with a diameter of 6 m and length of 3,145 m under the Bosporus Strait. This is the most complex section of the engineered route for a more than 150km pipeline within the Melen project, which is being constructed to provide citizens of Istanbul with water from the Melen River. The system must satisfy demand of the citizens for potable water till 2040. Capacity of the unit is designed for 750,000m3/day.

In January 2006, OAO Mosmetrostroy in the consortium with ZAO Association Ingeokom and two Turkish construction companies Alke and STFA won the tender for construction of a hydraulic tunnel under the Bosporus Strait at a depth from 0 to 140m with a slope of 7.439%. The tender was announced by the Ministry of Natural Recourses of Turkey.

A team of skilled specialists of OAO Mosmetrostroy and SMU Ingeokom was composed for work on the project.

The Herrenknecht Company engineered and fabricated – with regard to the characteristics of geological conditions – a powered earth pressure balanced tunneling complex with a diameter of 6.15m.

A great challenge for drivage was advanced exploration drilling each 40 meters, which allowed exact determination of geological structure, boundaries of unstable areas, inflow of water, and accordingly actins for soil stabilization.Assembly of the powered tunneling complex started in December 2007, while the drivage started in February 2008.

The following was done to stabilize soil in unstable areas and suppress considerable inflow of water: - Injection of cement grout and polymer compositions in the front of the heading; - Injection of polymer compositions behind the lining for leakage elimination; - Construction of a “support ring” from polymer compositions for reduction in water inflow. Construction of the tunnel was completed in April 2009. Currently, powered tunneling complex has been disassembled via a shaft with the diameter of 8m and depth of 140m. Maximum weight of components was 96 tons.

That was the first experience of such large-scale overseas works for Moscow Metrostroy. The opening ceremony dedicated to completion of the facility, which is unique in terms of its realization techniques, took place on the 2nd of May 2009.

Employees of Moscow Metrostroy succeeded in connecting of two continents with a tunnel for 15 months. Successful drivage results under extremely difficult geological conditions are another evidence of the Russian tunnel engineering level.