1st International Congress on Tunnels andUunderground Structures in South-East Europe „USING UNDERGROUND SPACE“ April 7-9, 2011, Dubrovnik, Croatia

Construction of two underground stations in city - Republic of (Design&Build)

Milomir PAVLOVIĆ Dipl.Ing., Interkoop, Belgrade, Serbia, milomir.pavlovic@interkop.com Zoran JOKSOVIĆ Dipl.Ing., DuoDEC Belgrade, Serbia, [email protected]

Summary:

Construction of two underground stations of the first phase of first metro line in the city of Almaty, Republic of Kazakhstan, is presented in this professional work. Almaty metropolitan was constructed under very complex construction conditions (geology, traffic, configuration, seismic, climate etc.). Metro stations, constructed by Energoprojekt are underground stations placed at great depths of 40 and 70 m.

Construction method was modified NATM, without anchors, but with pipe roofing.

Company "Energoprojekt", from Belgrade, Serbia, has joined the project since 2006 as the only foreign construction company. For less than four years, "Energoprojekt" built two underground stations. As there were no accurate designs, the contract was Design&Build type. Design service, (existing design check and adjustments, main design for NATM structures, structural analysis, shopdrawings and design site supervision), was provided by DuoDec, specialized consulting company form Belgrade, Serbia.

Keywords: metro station, NATM, top heading, invert, construction stages

1. About metro in Almaty

Almaty is the largest city in Republic Kazakhstan, with 1.5 million population. As the former capital of Kazakhstan and the first city of a million in that region, by Soviet standards, in 1983 it was decided to build a metro.

Building of metro lasted until 1996, when the collapse of the and the fall of the economy, caused the suspension of works. Until that moment, the preliminary design and preparation works for about 4.0 km. of parallel transport tunnels for the first phase of the first line of were completed. The works continued in 2003. When there was a significant economic development of the state and the expansion of civil engineering.

Almaty is located in the south eastern part of Kazakhstan. There is harsh Fig. 1 Almaty location continental climate with cold winters and hot summers. The city lies on the slopes of Altai Mountains at an altitude of 600900m. Almaty is located in earthquake prone area with significant seismic activity of 9 degrees (Merkalli scale). Geological environment for the building is very unsuitable, and it consists of glacier layers of unbound materials, granite and granodiorite. Particles of dust and clay, mixed with rock material as well as the compression achieved by longstanding natural consolidation make it conditionally stable.

1st International Congress on Tunnels andUunderground Structures in South-East Europe „USING UNDERGROUND SPACE“ April 7-9, 2011, Dubrovnik, Croatia

1.1 Participants in the construction

Investor of metro system is the administration of Almaty (City Government) that participates in the financing with 15%, while the remaining 85% is cofinanced from the budget of the Republic.

The designer is company "Metroprojekt" from Almaty with significant involvement of design organizations from Tashkent, and St Petersburg. In 2005, Austrian company "Beton und Monierbau" completes the new, NATM based design of "Zibek Zoli" metro station.

The General Contractor is "Almatimetrokorilis". It is a stateowned company established to build a metro in Almaty. Company, "Energoprojekt Civil Engineering" from Belgrade, Serbia has carried out construction works on two underground metro stations: "Almaty" and "", as the only foreign construction company on this project As there were no accurate designs, the contract was Design&Build type. Serbian consulting company, "DuoDEC" from Belgrade provided design service, for "Energoprojekt ".

1.2 The metro lines in Almaty

According to general plan of Almaty, there are planned three lines as follows:

The first line, to be built in two phases: • The first phase makes the underground part of 8.5 km length • The second phase consists of continuation of the line, of 12 km length, where the tunnels are built using a TBM, while building of metro station is provided in an open excavation.

The second line of 10 km length connects the first line with the airport.

Due to poor underwater terrain it will be the third line closes the transport ring around the City centre and at two points it crosses the first line. For this line has not been adopted the position Fig. 2 Almaty metro lines (underground or aboveground) yet, as well as the type of structure, provided to work in an open excavation.

It should be noted that the terrain is mostly sloppy. Harsh continental climate and significant vegetation, the most probably affected the aboveground position of this line. Traffic flows, population density as well as location of important buildings have caused different position of metro lines and different type of structure

1.3 Types of structures for metro stations at the first phase of the first metro line

The first phase of the first line is built as a deeplying line in the very city centre, 8.5 km in length. It consists of two parallel tunnel tubes with a diameter of 5.5 m each and wheelbase of 21m. They were performed by mechanized shield (TBM) with four construction starting points from stations Raimbek and , which were performed as Cut and Cover structures. At the first phase of the first line, were built seven metro stations (two as C&C and five underground deeply placed stations), and there were applied three types of structures.

1st International Congress on Tunnels andUunderground Structures in South-East Europe „USING UNDERGROUND SPACE“ April 7-9, 2011, Dubrovnik, Croatia

TYPE 1 Metro station Raimbek is arched box construction built in open excavation under the protection of RC piles. Metro station. Alatau was constructed as cut and cover structure, with temporary protection of slopes and secured by a steel mesh and shotcrete

TYPE 2 Metro stations "Zibek Zoli" and "Almaty" are underground metro stations comprising vestibule, sloping tunnel and platform structure at the level of platforms. It consists of three independent tunnel tubes that were subsequently fused with transverse passes to form joint platform construction. This is, so called, "Three tubes" structure.

TYPE 3 Metro stations: Abaya, Bajkonor and Tulpar are underground metro stations, where construction at the platform level, consists of three RC vaults with common RC walls (columns), called "Columntype" structure. Fig. 3 Station types

2. metro station

2.1 Description

The bottom of the station is 37 meters below the ground level extremely bad geotechnical conditions 9th zone of seismically activity. The station consists of the main platform, approach corridor and technical premises the main platform consists of the 3 tubes, 2 side tubes 115 m long each and the middle tube 104 m long which serves for the passenger approach. During the construction tunnel tubes are separate and independent but upon the completion of construction they are being connected with cross corridors on each 10 meters.

The approach corridor is the extension of the middle tunnel tube, it is 45 m long and leads to Fig. 4 Station Almaly cross section the sloping side tunnel with escalator.

The technical premises follow the approach corridor with the total length of 45 m. Cross sections of the approach corridor and technical premises are the same but different from the cross sections of the station tunnels.

Each tunnel was build independently, using NATM, which consists from the following steps: • embedding of steel pipes Ø114/6 mm which make so called "pipe roof" excavation, • shotcrete lining made of shotcrete reinforced with welded wire mesh and steel arches, • waterproofing and inner lining made of reinforced concrete

1st International Congress on Tunnels andUunderground Structures in South-East Europe „USING UNDERGROUND SPACE“ April 7-9, 2011, Dubrovnik, Croatia

2.2 Almaly metro station -facts

• total structure works value 21. mil. $ • total area of station platform is 1950 m 2 • the bottom of the station is 37 meters below the ground level • extremely bad geotechnical conditions • 9th zone of seismicall activity • the station consists of the main platform, approach corridor and technical premises • the main platform consists of the 3 tubes, 2 side tubes 115 m long each and the middle tube 104 m long which serves for the passenger approach. During the construction tunnel tubes are separate and independent but upon the completion of construction they are being connected with cross corridors on each 10 meters. • the approach corridor is the extension of the middle tunnel tube, it is 45 m long and leads to the sloping side tunnel with escalator. • the technical premises follow the approach corridor with the total length of 45 m. Cross sections of the approach corridor and technical premises are the same but different from the cross sections of the station tunnels

Fig. 5 Station Almaly layout and longitudinal section

• each tunnel was build independently, using NATM, which consists from the following steps:  embedding of steel pipes Ø114/6 mm which make so called "pipe roof"  excavation  shotcrete lining reinforced with welded wire mesh and steel arches  waterproofing  inner lining made of reinforced concrete

• excavated 37188 m 3 of soil • embedded:  6850 m 3 of shotcrete  12840 m 3 of concrete  1604 t reinforcement steel bars  14428 m 2 of waterproofing • shotcrete lining 081.2 m/ day • inner lining 2.0 m/ day

1st International Congress on Tunnels andUunderground Structures in South-East Europe „USING UNDERGROUND SPACE“ April 7-9, 2011, Dubrovnik, Croatia

2.3 Construction method of Almaly metro station

Construction at the platform level is located at 37m below the ground surface and consists of a station area, access corridor and technical premises. The station area consists of three independent tunnel tubes, the two side tubs where the trains pass through, long 115m each, and a middle tube for passenger access, 104m of length. The contraction assumes the excavation with of temporary lining, construction of inner lining and platform structure. Execution is done from the preprepared but the cross corridor.

Fig. 6 Station Almaly render

2.3.1 Shotcrete lining

Shotcrete lining based on NATM consists of pipe roofing , the shotcrete thickness of 30 cm in the top heading and 40 cm in benches and invert with three wire mash and steel girders, which together with shotcrete, form RC arches at a distance of 1.0 m. Excavation and lining of lateral tubes is done with the simultaneous dismantling of transport tunnel tubes. During the excavation and lining is strictly respected the process which provides the uniform progress in cross section and longitudinal section, so that all activities excavation and lining of the full profile are to be completed in 12m length, maximum. Fig. 7 Sections in the phase constructions

Fig. 8 Pipe roofing Fig. 9 Steel giders

For excavation and construction, a modified NATM technology, is applied. It is constructed in full profile under the protection of the screen. Pipe roofing is made of 27 perforated steel pipes, Ø114/6 mm, piled in length of 10.5 m, which is injected through the injection supply pressure, which connects the unbound materials and thus makes the protective screen. Excavation and construction are made in three phases: Top heading in steps 4x1.0 m, benches in steps 2x2.0 m and invent in steps 1x4.0 m.

1st International Congress on Tunnels andUunderground Structures in South-East Europe „USING UNDERGROUND SPACE“ April 7-9, 2011, Dubrovnik, Croatia

Fig. 11 Steel tubes removing

Fig. 10 Calculation of shotcrete lining

For monitoring of strain (deformation), there were constructed 5 rappers in profile, in every two meters, which were measured, on a daily basis, the convergence of the tunnel. In addition, the soil surface was performed auscultation.

It is interesting that, despite the fact that the inner lining was elastic at measuring convergence and auscultation were not revealed displacement greater than 23 mm, which are primarily the result of measurement error or physical displacement of rappers during the working process of machines. It can be concluded that the primary lining had sufficient capacity and that there has not been movement in the rock material i.e. to the development of mountain pressures. This allowed us to elaborate tunnel tubes in full length and then organize the creation of inner lining. Primary lining in the other lateral tunnel tube was possible only after completion of min. 30.0 m of inner lining in the first lateral tube. Excavation and primary lining of the middle tunnel tube was carried out after the completion of right and left tube inner lining.

2.3.2 Inner lining

Fig. 12 Waterproofing invert Fig. 13 Reinforcement invert

1st International Congress on Tunnels andUunderground Structures in South-East Europe „USING UNDERGROUND SPACE“ April 7-9, 2011, Dubrovnik, Croatia

Fig. 14 Reinforcement top heading Fig. 15 Final works

At the shotcrete lining, firstly is set PVC waterproofing, d = 2.0 cm at the layer of geotextile. The inner lining was performed in two phases: • Construction of invert in section of 10.0 m. • Construction of benches and top heading of the tunnel, also in section of 10.0 m.

The steel formwork, made in Almaty, was applied, according to our original design. Hydraulic equipment and gear for the transfer of formwork is made in Serbia. Due to the extremely thick inner lining, formwork itself with access to transmission was weighting about 80 tones The amount of concrete in one box section of 10m, ranged from 180 200 m3 per section.

3. Abaya metro station

3.1 Description

Metro Station Abaya is, due to its location (distance about 4 km from the Portal and the depth of 72 m from ground surface) and the worst geological conditions with significant articipation of major rock singles, considered the most complex to perform. The construction of station has requested a different, much more complex construction method.

The station consists of station area, access corridors and technical rooms. Station platform surface is 1.495m2. The structure of platform area consists of three arches with common row of columns.

Cross sections of lateral tunnels were significantly larger surface area, about 100 m2. With their own profile, they provide and make joint pillars of inner lining. In construction of lateral tunnels was used NATM technology where the length of the protective screen done Fig. 16 Station Abaya cross section by roof piping, remained 10.5 m but due to stability it was preformed in blocks of 7.0 m.

Lateral tunnels are also preformed in three stages with a maximum of strict application of construction technologies. The elaboration of the central station area could be make only after finishing the inner lining of lateral tunnel tubes.

1st International Congress on Tunnels andUunderground Structures in South-East Europe „USING UNDERGROUND SPACE“ April 7-9, 2011, Dubrovnik, Croatia

Fig. 17 Central tube waterproofing Fig. 18 Station Abaya central platform Construction of central tunnel was performed in two stages: • Excavation and shotcreting with successively concreting the upper RC arch, sections of 5.0 m. • Excavation and shotcreting with successively concreting lower arch in sections of 10.0 m.

Shortly before construction of the inner lining, was done the installation of PVC waterproofing. Connecting PVC waterproofing of lateral tunnels with middle tunnel, was made much more difficult because of frequent damages during the demolition of temporary fortifications of lateral tunnels.

The inner lining on the lateral tubes was constructed in two stages: • Invert and a part of common wall until the hole, in blocks of 9.0 m • Top heading of tunnel with common wall where the the holes were left, was constructed in two sided formwork, in blocks of 9.0 m

3.2 Abaya metro station - facts

• excavation 31.300 m 3 soil • Construction period 22 months • embedded: • Total structure works value 31. mil. €  5406 m 3 of shotcrete • Total area of station platform is 1495 m 2  11100 m 3 of concrete • 72 m deep  1790 t reinforcement steel • The worst geotechnical conditions  11160 m 2 of waterproofing • 9th zone of seismic

Fig. 19 Station Abaya layout and longitudinal section

1st International Congress on Tunnels andUunderground Structures in South-East Europe „USING UNDERGROUND SPACE“ April 7-9, 2011, Dubrovnik, Croatia

4. Construction stages of Almaly metro station

1st International Congress on Tunnels andUunderground Structures in South-East Europe „USING UNDERGROUND SPACE“ April 7-9, 2011, Dubrovnik, Croatia

5. Almaty metro stations construction final

The working tehnology, on metro stations Almaly and Abaya, was very complicated because of the conditions of construction.

All works were performed according to the current legislation of R. Kazakhstan, and with application of mining regulations which are much more severe, in relation to our domestic regulations.

At the construction of transport tunnels and metro stations, at the same time worked 18 contracting companies that used the common traffic lines as well as the connections to the installation of General Contractor (electrical energy, compressed air, gray water, communications equipment and vertical transportation).

In construction of metro stations, we did not have the design documentation so we were forced to elaborate, on our own. Designconsulting firm DuoDEC from Belgrade, executes the design documentation for each phase, and coordinates the documentation with General Contractor and designer, in order to enable ENERGOPROJECT to implement it. This fact, despite the difficulties gave us some advantages in applying the NATM technology.

All the troubles and difficulties were granted with beautiful interior design work, that makes these stations much more than usual transportation spots. Opening of the first Almaty metro line is expected within 2011 year.

Fig. 20 Almaty metro tunnel Fig. 21 Station Zibek Zoli central platform

Fig. 22 Station Almaly central platform Fig. 23 Station Abaya central platform