Pedestrian underpass between ‘the Small Hermitage” and “The Large Hermitage”

At present the museum staff use Schuvalovsky passage between two buildings of the Hermitage museum complex to pass from building to building. But according to the new concept of the museum renovation, the passage will be soon opened for general public.  Therefore the creation of the underpass for the staff needs became relevant.

Project name: Underground passage between the Small Hermitage and the Large Hermitage
Customer: The State Hermitage Museum
Key contractor: LLC “Beta-Com”
Site: Saint Petersburg, the Palace embankment, 34-36
Start of the construction: 25.12.2014
Time limit: 01.10.2015

The work above the ground started at the end of 2014 from the shoring of the foundations of the old buildings and waterproofing.  The walls in the sector of the future passage were reinforced with the secant piles. The concrete grouting was performed under the future base slab with the jet-grouting technology. This technology allows creating the resilient layer of stabilized soil. Being integrated with the enclosed structure, this technology makes development of the strains in excess of industry norms impossible.  

The work to drop down the historic level of the floors and construction of the new concrete floors was carried out along. The complexity of the structure is defined by geological conditions. The vicinity of the Neva River makes the ground waters level reasonably high. With the lowering of the foundation the water starts to fill in. It starts to appear at the depth of 1 m for the Large Hermitage building, and it is 80 cm from the floor level for the Small Hermitage.

The pit was constructed with the depth of 1.5 m in the soils that include clays and coarse clastic limestone and granite boulders as well as the fragments of the bricks used for old basements. Many longitudinally placed groundsills of stained larch tree were discovered deeper, the groundsills rested on wooden piles that went deep into the ground.

The heavy equipment could not freely access the construction site, so the builders had to excavate the soil manually, to reduce the remains of the wooden basements and carefully lift it all up on the above ground level. The design work was delayed almost by the month because of it.

According to the design, the base stab is placed lower than the Baltic Sea level. With the wind blowing from the sea, the water rises and the construction work has to be carried out basically in the water.

In order to regulate the water streams the special pipes were placed along the perimeter of the pit. These pipes lead the water into the special drainage pit outside of the concreting area and later pumped away upon reaching the certain level.

Reinforced concrete structure is anchored on the piles.  Additional reinforcement of the lowest stab of the passage was performed.

In a while after the settlement of the soil, the concrete may go fractured. The expansion joints are used to avoid reinforced concrete structures collapse, these joints segregate the stab into several parts.  

Such a system makes the structure more resilient, reduces the weighting and prevents the appearing of the cracks.

Along with reinforcement work the mantling work and waterstops weldment were carried out. Before the concreting, the waterstop is fixed with steel rails, so after the concreting the lowest part of it would be in concrete, the upper would stay on the surface for further attachment to the reinforced concrete wall.

The slim perforated injection hose is placed in the places of the joints of reinforced concrete stabs. Hose edges are tugged on the surface of the structure with packers attached to the lining. In case of leaking, special injection material is pumped through the packers, it goes along the hoses and waterproofing the structure.  The joint becomes waterproof and thanks to its elastic properties stays resilient to adjustments

At present all the work in regard of reinforced concrete structure is completed in the basements of both buildings, the stairs and passage to the service room are constructed.

All monolithic and waterproofing work will have been completed by the end of August, the project will have been completed by the end of September.