Underground construction. Underground parking at "Alfa-Arbat-Center" Multifunctional Business Center in Moscow

The construction of underground parking under the "Alfa-Arbat-Center" Multifunctional center under construction was executed in particularly important historic and cultural value area on the corner of Arbat street and Gogolevsky boulevard.

The construction specifics were complicated by close proximity of three protected buildings, common collector, "Arbatskaya" shallow subway station and Filyovskaya line tunnels.

Initially the general contractor (firm "SKANSKA East Europe" Oy) adopted cut-and-cover construction method with a temporary metal two-tier support of excavation enclosure made of beam belts, pipe buntons and knees (DWF-drawing, 13.6 Kb), (DWF-drawing, 13.4 Kb).

Data of preliminary survey show that geological composition of construction site is:

4-6.5 m fill up soil with admixtures of construction debris ad underlayer of peated loam;

6 m clayey middle-sized and coarse sands with gravel and boulders;

up to 3 m semi-hard loam and hard loam with boulders and gravel;

2 m crushed stone and gruss of limestone;

up to 3.5 m argillite-like hard clay;

3 m Perkhurovsky eroded and fissured limestone, medium strength, eroded to small blocks and crushed stones;

1.5 m fissured and dense Perkhurovsky dolomites;

6-7 m argillite-like hard and semi-hard clay.

Subsoil waters were predicted to be 1-2 meter above the foundation slab of the underground 4-level parking.

The pit will be enclosing by in-situ reinforced diaphragm walls, thickness 60 cm, which acted as anti-filtration structures at the same time.

Taking into account the cut-and-cover construction method consolidation of nearby buildings foundations was executed before the erection of diaphragm walls according to the design of Gersevanov research institute of bases and underground structures (NIIOSP).

Diaphragm walls were constructed with application of hydraulic grab equipment and using technology developed by the French company "SOLETANCHE BACHY".

Waterproofing of joints between panels provide by special synthetic insulation tapes а "Waterstop".

Trench excavation was made by portions of 5.6 to 7.6 m length by grab with 2.7 m opening and close to existing buildings – by portions of 2.7 m length. The quality of diaphragm walls connection was guaranteed due to using of L-shaped corner portions. High quality of joints between panels (to exclude any mud joints) guarantee by removable stopends ("Stopsol") of preliminary trench portions, as well as by preliminary excavation of secondary and following portions of trench until removed.

In compliance with the expected bedding of Perkhurovsky limestone layer that cannot be excavated by a grab, the project envisaged construction of diaphragm walls of 23.9 m depth in the places of their roof considerable erosion and of 21.4 m – in the rest area. Such deepening provided the required bearing capacity of the walls along the base for the possibility of 13-floor building placement over the underground parking.

However while constructing the diaphragm walls there appeared discrepancies between the actual depth and the expected one of the mentioned layerbedding. As a result the diaphragm walls were constructed for the depth of 19.5-20 m only. Nevertheless this depth was enough both for the cut-and-cover construction of the 4-level underground parking with a 2-level temporary metal support and for the planned future construction. Moreover, by means of embedded metal pipes fixed in reinforcing cages grouting of eroded Perkhurovsky limestone and dolomite was executed in the footing of diaphragm walls for the depth of 5 m from their bases.

Reinforcement of diaphragm wall panels was selected in a complete accordance with calculation phases connected with peculiar features of soil excavation in the pit, sequence of temporary metal support installation and consecution of erection of bearing reinforced concrete structures.

It was taken into account that during operation of underground parking the diaphragm walls will be supported by foundation slab, 3 floor slabs and roof slab at surface level. The walls will receive additional load from superstructure building to be constructed on top of the car parking.

The results of our geomechanical calculations made at the beginning of 2001 showed that the estimated consolidation of foundations of neighboring buildings only from side of underground parking under construction is not at all sufficient (additional consolidation of foundations of inner walls is required and it must be deep enough), but there is no threat to destruction of "Arbatskaya" subway station of Filyovskaya line.

Displacements by axis X

Displacements by axis Z

Basing on the geotechnical forecast of the nearby buildings deformation wile using the cut-and-cover construction and taking into consideration narrow construction conditions we strongly recommended to the general contractor during more than half a year to turn to the top-down construction method and to the developer – to change the designers unqualified in underground construction.

After the completion of the short-cut diaphragm walls designed for the cut-and-cover construction the developer – JSC “SYRACUSE” made a decision about the increase of the number of underground parking floors from 4 to 5 and advance construction of the Complex main building with respect to the underground parking.

In November 2001 taking into account existing situation JSC “SYRACUSE” placed a direct order to us for the basic technical solutions project giving the possibility to compare the variants of the cut-and-cover and top-down methods and to make a proper decision.

Excavation of trench portion using hydraulic grab equipment.

Joining of reinforcing cages on the construction site.

Construction of the MFBC “Alfa-Arbat-Center” main building.

Preparation of placing of bored-column’s reinforcing cage.

It took a few months to become sure of advantages of top-down construction method of 5-level underground parking and to get the agreement of Moscow metropolitan as the distance between the cemented footings of bored columns and the tunnels crown was about of 5.5 m.

Isofields of principal stresses N3 in soil massif after the completion of underground parking construction and before the erection of the 13-storey office building over it.

In January 2002 JSC “SYRACUSE” signed a contract with us on designing of all bearing structures, waterproofing, general and special geotechnical technologies for the underground 5-level parking construction by the top-down method.

For the first time in Russia on this site applying “know-how” by Pavel B. Yurkevich while constructing multilevel underground parking by the top-down method together with floor-slabs not only the lift and stairwells were constructed successfully but the entry lacet ramps as well. This innovation allowed to use the ramp structure as the permanent support during each construction stage, to deliver building materials and compact products, to hand in the completed upper stores for finishing and installing engineering services in parallel to the construction of lower one (DWF-drawing, 89.1 Kb).

In September 2002 the lease of private territory adjacent to the underground parking expired and the construction site area decreased to the size of building up directly (about 2800 m²). There was but one solution to place the construction site onto the underground parking roof-slab was unrealizable. Due to the necessity of constructing over the underground parking a 2-storey technological annex to the Complex main building in the shortest possible time the real area of construction site was diminished to 1000 m² (DWF-drawing, 33.8 Kb).

Taking into account the fact that site area decreased and the diaphragm walls were estimated for a 4-level underground parking construction by cut-and-cover method and had an unplanned depth the designing and construction of a 5-level underground parking by the top-down method became both unique and masterly.

          Completion of construction…

          Publications…
          Patents…
          Drawings catalogue…

Concreting of the bored-column with a centering device.

Cementation of eroded limestone in the bored-column base.

Qualifying geological survey core sample selected in the bored-column base before cementation.

Soil openworking in the excavation pit of the first level at the car parking first half-part.

Blinding before concreting on the ground of the floor-slab above the -2nd storey on first half-part of the parking. Territory preparation before concreting on the ground of the roof-slab on second half-part of the parking.

Execution of junctions between bored-columns and floor-slab above the -2nd storey.

View of the constructed main building from the first level excavation pit.

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