The Mosmetrostroy subsidiary LLC MMS International is completing the modernization of the Vladivostok tunnel of the Far Eastern Railway (Stalin Tunnel). In the second quarter of 2019 it will be opened for passenger electric trains. Why for unique objects there is no single recipe for their successful renovation, says Andrey Kuzmin, deputy head of the design and construction group.
With the start of modernization, the movement of passenger electric trains in the tunnel stopped - the contact wire was dismantled. All work was carried out in technological “windows” of 15 and then 12 hours. This mode made it possible to continue freight transportation using diesel locomotive traction at night. The project is now coming to an end. This spring, the first electric trains will carry passengers through the updated tunnel.
About 200 people and more than 30 pieces of equipment were involved in the modernization. Engineering and technical specialists were recruited from among MMC International employees. Workers were recruited mainly locally (Far Eastern region). But some of them, highly professional foremen and tunnelers, were also sent to Vladivostok from the capital.
“The project was divided into two stages,” explains Andrey Kuzmin, deputy head of the MMC International design and engineering group. – Preparatory work began in the summer of 2016. The task was to stop the flow of water into the tunnel and stop the development of degradation processes in its lining. Water seeped through everywhere, it could even get onto the contact wire, and there were active leaks in many areas. In winter there was a lot of ice. Ice deposits on the walls and roof of the tunnel threatened the safety of train traffic.
Water inflows are groundwater and sediments that penetrated into the tunnel. It took a whole range of measures to suppress them. First, cement-sand and cement-silicate mortars were pumped behind the lining, eliminating voids and cavities between it and the ground.
Then this space was sealed. A network of holes was drilled across the entire lining area. Then, domestically produced hydroactive polyurethane resin was pumped into them using pumping equipment. This one-component composition, upon contact with water, begins a reaction and expands up to 30 times, filling the remaining pores and cracks and binding the soil mass. We also sealed expansion joints and damage in the tunnel lining.
– For injection work (injecting special compounds into the tunnel lining. – editor’s note) there is no single recipe for success. At each specific site, it is necessary to select a specific composition, injection mode, and hole spacing. At first I had to tinker. After we injected the experimental area, selected all the necessary parameters and made minor adjustments to the project, things went fine,” shares Kuzmin.
At the same time, we drilled and equipped wells for lining drainage. They are necessary to remove the maximum possible amount of water from the lining and reduce pressure. Drilling was carried out on one side from a drainage adit 1140 m long, located parallel to the tunnel, on the other, from the lining drainage chambers (CDC).
Later, as part of the main stage, a reverse vault of the drainage adit was built with the arrangement of a drainage tray and water outlets from the KZD. The reinforced concrete lining of these structures was brought to standard condition.
At the same time, we were developing a project for the main stage of modernization. It began after the winter of 2016-2017, when the main water inflows were suppressed. After draining the tunnel, we moved on to restoring and strengthening the lining. We performed a preparatory (leveling) layer and sprayed waterproofing with the property of double-sided adhesion (equally strong adhesion to the surface to which it is applied and to the material with which it is covered).
At this stage, difficulties were caused by the climate characteristic of Vladivostok. Due to the proximity of the ocean, the air humidity at the facility reached 100%, with negative temperatures added in winter. Waterproofing under such conditions polymerizes poorly and does not achieve the required performance. The builders cut off the work areas with “curtains”, heated and dried the air and the lining surface with heat guns.
A special thixotropic composition with polymer and metal fiber was applied on top of the waterproofing using the “spray” method, which formed a working layer 100 mm thick. The result was a multi-layer lining, which included both the existing one - rubble concrete, and the new one - high-tech.
As part of the main stage, the upper structure of the track was reconstructed. It was made ballastless (on small reinforced concrete frames) along the entire length of the tunnel. In the area where the structure was the same before the modernization began, 40 defective frames were replaced.
At the approaches to the tunnel, a major repair of the track was carried out with the reconstruction of the bridge over the Buyakovka River. The drainage systems were completely rebuilt. To prevent ice from forming in winter, a heating cable was installed in new drainage trays built along the sides of the tunnel. We also reconstructed all water supply and maintenance facilities at the portal sites.
Modernization also affected the tunnel portals. Restoring them while preserving their historical appearance was an important condition. The Stalin Tunnel is a cultural heritage site of regional significance. The red letters with the name, knocked down in 1959, during the period of debunking the cult of the leader’s personality, returned to the entrances.
– The project is nearing completion. The working layer of the lining is completely ready, the contact network is half installed. All that remains is to hang the contact wire, complete the construction of utility systems, remove the wooden flooring for the passage of construction equipment and lay 1,700 meters of continuous track,” summarizes Kuzmin.
The Stalin Tunnel was opened in 1935. Its length is 1382 meters, the height from the level of the rail head to the roof of the arch is 6.5 meters, the width is approximately 5.3 meters. The facility is located on the Staraya Rechka – Cape Churkin section in the Leninsky district of Vladivostok. The geology of the site includes moderately and highly fractured, water-logged rocks. Above the tunnel there are buildings and structures, roads, railways, a network of above-ground and underground utilities.
Over the 80-odd years of the tunnel’s existence, attempts to repair it have been made more than once. All of them were unsuccessful. From 1989 to 1991, the tunnel was excavated, but it was never completed. From 1993 to 1998, the construction of a ballast-free track took place; in 2001-2002 it was resumed, but again was not completed. At the same time, a central collector was built - a reinforced concrete pipe with a diameter of 300 mm. In the early 2000s, they tried to carry out bitumenization: they pumped cement mortar and hot bitumen behind the lining of the tunnel. But this undertaking did not produce significant positive results.