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2. SMART Tunnel in Malaysia

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What is meant by SMART?

Stormwater Management And Road Tunnel

A very ingenious, innovative, ambitious and first of its kind in the world of engineering solution for combining stormwater relief and road traffic into a single tunnel.

An indigenous MALAYSIAN idea!

SMART Tunnel Project in Kuala Lumpur, Malaysia

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• STORMWATER MANAGEMENT AND ROAD TUNNEL (SMART):

A BYPASS SOLUTION TO MITIGATE FLOODING IN KUALA LUMPUR CITY

CENTER, MALAYSIA

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Stormwater Management and Road Tunnel Project (SMART) involves the construction of:-

� A 9.7 km long by 11.8 m internal diameter bored tunnel

� Six hydraulic structures � Two detentions ponds � A 0.5 km long release culvert � Numerous other auxiliary facilities such as motorway ingress / egress structures

� Vent cum surge shafts and a flood detection system

� The central 3 km length of the tunnel will also be used as a two-lane double-deck motorway.

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The project objectives are to

� Mitigate over-bank flow nearby Tun Perak Bridge located at Kuala Lumpur city center.

� Relieve traffic congestion at the main southern gateway (KL-Seremban Highway) into the city.

6Figure 1: SMART

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Schematic Layout Plan

Figure 2: Schematic Layout

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Schematic Layout Plan

Figure 3: Schematic Layout

9Figure 4: Objectives of SMART

10Figure 5: Objectives of SMART

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SMART Project Data

Figure 5: Project Data

12Figure 4: Special Features

13Figure 5: Safety Features

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Table 1: Flooding incidences in Kuala Lumpur city

1996, 1997, 30-Apr-2000, 26-Apr-2001, 29-Oct-2001, 11-Jun-2002, 10-Jun-2003

791996 to 2004

1986, 1988, 1993, 19954101986 to 1995

19821101976 to 1985

19711161950 to 1975

19261-Before 1950

DATESNO OF TIMES

INTERVAL (years)

PERIOD

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Following the 1971 event, the Government has carried out studies to

� Understand the flood problems in the river basin.

� Identify principal causes of flooding.

� Investigate flood mitigation measures.

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Resulting from the studies, Klang River Basin Flood Mitigation Project (KRBFMP) was formulated and subsequently implemented in phases. During the implementation of the KRBFMP, midcourse appraisals were conducted to investigate necessary follow up plans. The reviews suggested that:

� Flood magnitudes in the city have further escalated. � This was largely due to the intensity of land development. � The computed 100-year average recurrence interval (ARI)

flood peak at Tun Perak Bridge is now about 430 cumecs instead of the original 353 cumecs on which the KRBFMP design had been based.

� New points of constrictions have emerged in Sg Klang particularly along the stretch upstream of Masjid Jamek.

� These were related to infrastructure development that encroached into the river corridor.

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INCEPTION� On 26-Apr-2001, Sg Klang overflowed its banks and severely flooded

the nation’s commercial hub at the city center stretching between Tun Perak Bridge (near Masjid Jamek) and Dang Wangi Bridge.

� Shortly after the event, the project proponent initiated a partnershipbetween the Government and private sector. They invited the engineering consultant to prepare a technical proposal aiming atcomplementing the ongoing KRBFMP to alleviate over-bank flow adjacent to Tun Perak Bridge (near Masjid Jamek).

� Then in May 2001, the first proposal comprising construction of bypass culvert and attenuation pond was conceived.

� The initial concept has since developed to the first dual-purpose tunnel of its kind in the world, Stormwater Management and Road Tunnel Project (SMART), embodied seemingly conflicting objectives.

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Figure 6: Schematic longitudinal section -flow through bypass tunnel

SMALL STORM (CATEGORY 1)Attenuation Pond

Holding Pond

Holding Pond

Attenuation Pond MODERATE STORM (CATEGORY 2)

Attenuation Pond MAJOR STORM (CATEGORY 3)

Holding Pond

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Design of the Tunnel

Figure 7: SMART Project Components

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� In November 2001 the outline of the scheme was based on a 9.7km long 11.83m internal diameter bored tunnel (Figure 1).

� The central 3.0km length would also serve as a highway tunnelby providing two decks.

� The upper deck provided two 3.35m wide traffic lanes and an emergency lane flowing South and the lower deck make similar provision for traffic flowing North.

� There would only be enough space for cars and the maximum vehicle height was restricted to 2.55m with a clear height between decks of 3.2m.

� The only other example of a two-deck road tunnel within a circular bore was the A86 in Paris which was then under construction.

� The design speed was 60km/hr with an indicated speed limit for traffic of 50km/hr.

Design of the Tunnel

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Design of the Tunnel

The tunnel can operate in three modes (Figure 8).

� with the whole tunnel dry.

� with the tunnel upstream and downstream of the highway section flooded and with water flowing beneath the invert of the lower deck but with the road decks open for traffic.

� with the highway decks closed to cars and open to water flow.

Figure 8: Three mode operation

22Figure 9: SMART Operation

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Tunnel Lining Design

� A modest quantity of reinforcement (90kg/m3) in the 500mm thick, C50 N/mm2 concrete

� Optimisation resulted in 1.7m wide segments in a ring comprising eight segments and a key

� The minimum radius of 250m was achieved by detailing the rings with a 110mm double taper

� The external water tightness of the tunnel was achieved with an EPDM rubber gasket designed for 32m head of water

Figure 10: Tunnel Arrangement

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Tunnel Waterproofing Design

Figure 11: Waterproofing

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Precast Concrete Lining Fabrication

Figure 12: Precast Concrete Lining

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Precast Concrete Lining Installation

Figure 13: Installed Precast Concrete Lining

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Road Deck Formwork System

Figure 18: Cross Section of Double Deck with System Formwork

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Road Deck Formwork System

Figure 19: Double Deck with System Formwork

Figure 20: Completed Double Road Deck

29Figure 21: Method of Construction

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Selection of Excavation Methods

� The results of the initial phase of site investigation showed that limestone rock was generally considered competent, with an average Q value assessed from cores of 22, a scheme was prepared for excavating this length by drill and blast with typical support classes showing rock bolts and shotcrete.

� Consideration was given to mitigating two particular risks.

� Firstly there were risks in encountering a mud or water filled void unexpectedly placing at risk the safety of the staff in the tunnel and possible consequent settlement of surroundinginfrastructure and buildings.

� Secondly the tunnel runs at shallow depth below an urbanised area so that objections to blasting would be expected. Vibrationlimits were set at 12mm/s at buildings and 25mm/s elsewhere, hours of blasting were to be restricted to within 150m of buildings.

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Selection of Excavation Methods

� As more site investigation results came in it became apparent that the previous assessment of the central section being in rock was an over-simplication as rockhead level varied rapidly and there were several locations where it would dip below the tunnel crown

� Construction of a bored tunnel along this length using NATMtechniques would have been slow and costly and would in practice require systematic advance jet grouting from the surface. Therefore this length reverted to TBM excavation

� The main contractor elected to use two TBMs for all bored tunnel excavation as they carried less risk of environmental disturbance

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TBM selected for excavation

Figure 22: TBM machines used in SMART

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The Selection of the Working Methods and Tunnel Boring Machines for the SMART Project

GEOTECHNICAL INFORMATION

� that the ground conditions comprise a variable thickness of superficial deposits comprising mining backfill and alluvium overlying marble of the Kuala Lumpur Limestone formation

� These deposits occur up to around 30m thick and can generally be described as soft silty clay with typical STP ‘N’ values of 10 to 15

� The marble is referred to locally as limestone and is generally moderately strong to strong. The surface of the limestone is highly variable and is characterized by a number of solution features that extend below rock head by up to 20m. The mean strength of the limestone is around 50MPa but ranges from 11 to 86 MPa. The ‘Q’ value assessment, based on discontinuity logging gave a mean best estimate of Q = 22. Mixed face and blocky ground conditions are expected at several locations alongthe drive.

� Groundwater is generally around 1.5m below ground level

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� GEOTECHNICAL INFORMATION

Figure 23: Subsurface conditions of the project

35Figure 24: Proposed Alignment 1

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Figure 25. Selection of excavation method for the SMART Project. The “ACTUAL” line shows the selected method by using two TBMs on the North-and on the South Drives. The “PREVIOUS” line shows the methods considered initially. Both TBMs started from the NVS TBM LAUNCH SHAFT.

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Selection of TBMs

� Only two types of TBMs can provide active face support; earth pressure balanced machines and slurry machines

� The Earth Pressure Balanced (EPB) machines keep the excavated material in the excavation chamber and release it through a screw conveyor in a controlled manner to conveyor belts

� The speed of releasing the material defines the pressure kept in the excavation chamber to support the tunnel face

� The EPB machine needs to form plastic material in the chamber from the excavated soil or rock

� If the composition of the rock and soil is such that it does not form plasticdough, the screw conveyor cannot seal and the machine does not hold the pressure

� The problem can be improved to an extent by dosing conditioning materials into the excavation chamber or to the screw itself. The conditioning additives can be foams, different types of polymers and bentonite. The conditioning can marginally extend the usable range of theEPB machine towards the rocky or gravelly materials.

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Earth Pressured Balanced Machine

Figure 27. Schematics of an Earth Pressure Balanced (EPB) Machine

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� Slurry Tunnelling Machines (STMs) have the excavation chamber filled with pressurized bentonite slurry

� The slurry pressure defines the active face support pressure� These machines support the face in a very similar manner to diaphragm

walls, where the bentonite “cake” formed on the soil and the slurry exerting pressure on it from the inside supports the wall of the trench during excavation

� The excavated material is evacuated from the front excavation chamber (plenum) by circulating (pumping) the slurry with the suspended solids to the surface to a separation plant

� The finer sand and silt material, down to 75 microns, is cut out by various sizes of cyclones. The cleaned slurry is pumped back to the excavation chamber.

� The STMs are more suitable to work in a sandy, gravelly, rocky or mixed face environment

� The STMs however have difficulties in operating in clay. The separation plant does not cut the clay from the slurry, so frequent and costly bentonite replacement is necessary. Clay also tends to clog the rake and cause blockages and as a consequence sudden pressure surges in the slurry system.

Selection of TBMs

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Figure 28. Schematics of a Slurry Tunnelling Machine (STM).An illustrated example(Animation Clip)

Slurry Tunnelling Machine

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What were the expected tunnelling conditions which would define the type of shield for the job?

Geotechnical:� Over 70% of the tunnel is to be built in rock. � The rock is karstic with solution features, channels and interconnected

cavities.� The cavities may be filled with water, fallen rock, silt, sand and clay.� Highly variable rockhead/overburden thickness resulting in mixed face

conditions in a significant length of the drive.� The overburden may be alluvium, or, at the ex mining areas backfill of the

dredging operation with low STP values.� The groundwater table is close to the surface, generally 1-2m below it.� The permeability of the fresh limestone bedrock is low, of the fissured rock

may be high. � Karstic features may have extremely high permeability by channeling karst

water through chains of solution cavities.� Over two kilometers of drive on the north side is in full face soil.Geometrical:� Large, 13.25m excavation diameter.� Low overburden, maximum 1.5D minimum 0.9D.� Tight R=250m curves to follow roads and public land a far as possible.

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The usual way to select between the EPB and STM systems is to analyze the soil samples and draw particle distribution curves.

Figure 29. Hitachi Zosen’s proposals to select machines based on granulometry. The “Slime Type” machine refers to an STM operated with high density slurry

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Figure 12. Machine selection graph proposed by Herrenknecht. The STM is referred to as Hydro shield here. It clearly tends towards using STMs in the more gravelly mediums.

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Selection of TBM Machines

� At the time of the selection process the largest EPB machine ever built was around 11m diametre. The EPBs inherently need higher torque than the STMs. The required torque to run a 13.2m diameter EPB machine would have been much higher.

� There were also already several slurry machine of 13m or more diameter whereas the only EPB of this or greater diameter was the soft ground machine for the Groenhart Tunnel

� There are known difficulties in conditioning the excavated rockmaterial providing an unsuitable mix in the plenum to seal EPB screws with relatively high water pressure.

� These considerations narrowed the field by questioning the suitability and buildability of EPBs from the final selection. It became evident that the right type of the machine for the given requirements is the STM. So Slurry Tunnelling Machines were selected.

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Figure 30. This Herrenknecht chart indicates the right selection of machines in relation to the permeability of the ground. It proposes the selection of EPBs when ground conditions are homogenous and the excavated material is plastic. It finds the use of STMs in highly permeable non-homogenous rock/ground preferable. The rock illustration happens to show a cavity similar to ones found in karstic rock.

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In order to excavate the tunnel in the required time the performance requirements specified for the TBM included:

� Excavation of a 1.7m ring in 70 minutes averaged over five rings.

� Erection of a ring in 65 minutes averaged over 5 rings

� Availability better than 90%� An advance of 10 rings (17m) in 27 hours � As the alignment had to follow under existing roads the TBM was required to be able to negotiate curves of 250m radius and therefore an articulation joint was specified

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THE MAIN DATA OF THE STMS PURCHASED:

� Type: Mixshield� Length of machine: 71m� Two trailer cars on haunch rails� Weight of the machine: 2.500t� Length of the shield: 10.245mm� Weight of the shield: 1.500t� Thrust cylinders: 3x16=48Nos� Max. thrust: 94.500kN� Grout lines: 8Nos in the tailskin� Probe drilling: 2 rigs� Guidance: SLS T-APD � Tailseal: 3 rows of wire brushes� Soft, hard & mixed face capable

cutterhead� Support pressure control by air

bubble behind a “hanging”bulkhead

� Cutterhead weight: 300t

� Cutterhead diametre: 13.260m� Cutterhead drive: hydraulic with

4.000 kW electrical power� Mainbearing seal: max 5 bar� Torque: 24.400kNm� Rotation: 0-3 rpm� Spherical main bearing � Axial displacement through

bearing: 400mm� Displacement thrust force:

28.900kN� Disc cutters: 76 Nos; 17”� 16 drilling ports for ground

treatment ahead� Total rated power of the TBM

8MVA � Trailing cable: 200m 22kV� Pipe and rail lengths: 6m

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Herrenknecht Mixshields, S 252 & S253

Figure 31. The schematic longitudinal and cross sections of the Herrenknecht Mixshields, S 252 & S253 selected for the project.

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Figure 32. Support Plants Layout On-Site.

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Figure 33. Installation of 300ton cutting wheel

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Figure 34. First breakthrough of the Mixshield (Ø13.21 m) in Kuala Lumpur.

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• Link to Urban Tunnelling in Soft Grounds using TBM