SMART Tunnel (Stormwater Management And Road Tunnel)The
"Stormwater Management And Road Tunnel" or "SMART Tunnel",is a
storm drainage and road structure inKuala Lumpur,Malaysia, and a
majornational projectin the country. The 9.7km (6.0mi) tunnel is
the longeststormwatertunnelinSouth East Asiaand second longest
inAsia.The main objective of this tunnel is to solve the problem
offlash floodsin Kuala Lumpur and also to reduce traffic jams along
Jalan Sungai Besi and Loke Yew flyover at Pudu during rush hour.
There are two components of this tunnel, thestormwater
tunnelandmotorway tunnel. It is the longest multi-purpose tunnel in
the world.In 2011, the SMART tunnel received theUN Habitat Scroll
of Honour Awardfor its innovative and unique management of storm
water and peak hour traffic.It begins atKampung Berembanglake
nearKlang RiveratAmpangand ends atTaman Desalake nearKerayong
RiveratSalak South. The project is led by the government,
includingMalaysian Highway Authority(Lembaga Lebuhraya Malaysia=
LLM)and theDepartment of Irrigation and Drainage Malaysia(Jabatan
Pengairan dan Saliran= JPS)and also a company joint venture pact
betweenGamuda Berhadand Malaysian Mining Corporation Berhad(MMC).
The Kilometre Zero of the tunnel starts atSalak Interchange.
In 2001 the Government sought proposals for a solution that
would allow a typical flood of three to six hours duration to occur
without flooding the city centre. A tunnel that would allow floods
to bypass the centre was one way of achieving this, providing it
was coupled with temporary storage facilities to keep flows
downstream of Kuala Lumpur within the capacity of the river
channel. A group led by Gamuda engaged SSP, a large Malaysian
consultant engineering firm, and Mott MacDonald UK to develop
proposals for a tunnel with holding ponds at upstream and
downstream ends of the tunnel.Construction of the tunnel began in
25 November 2003. TwoHerrenknecht'sTunnel Boring Machines
(TBM)fromGermanywere used, including "Tuah" on north side and
"Gemilang" on south side.Gusztv Kladoswas the senior project
manager of the project.On 11 December 2003, the 13.2 m diameter
Mixshield TBM, Tuah, completed a 737 m section after 24 weeks of
excavation. By the end of January 2004, Tuah would start a second
drive covering a distance of 4.5km to Kampung Berembang lake. The
motorway sections on the SMART system was officially opened at
3:00PM, 14 May 2007, after multiple delays. Meanwhile, the
stormwater sections on the SMART system began operations at the end
of January 2007. As of July 18, 2010 the SMART system has prevented
seven potentially disastrous flash floods in the city centre,having
entered its first mode 3 operation only weeks after the opening of
the motorway.
The first mode, under normal conditions where there is no storm,
no flood water will be diverted into the system. When the second
mode is activated, flood water is diverted into the bypass tunnel
in the lower channel of the motorway tunnel. The motorway section
is still open to traffic at this stage. When the third mode is in
operation, the motorway will be closed to all traffic. After making
sure all vehicles have exited the motorway, automated water-tight
gates will be opened to allow flood waters to pass through. The
motorway will be reopened to traffic within 48 hours of
closure.Technical Specification : Stormwater Tunnel1. Construction
cost:RM1,887 million (US$514.6 million)2. Stormwater tunnel
length:9.7km (6.0mi)3. Diameter:13.2m (43.3ft) (outer diameter)4.
Tunnelling method:Tunnel Boring Machine(TBM)5. TBM type:Slurry
shield Motorway Tunnel1. Motorway tunnel length:4km (2.5mi)2.
Structure type:Double Deck3. Ingress and egress:1.5km (0.93mi) at
Jalan Sultan Ismail and Jalan Imbi4. Length:1.4km (0.87mi) at Jalan
Tun Razak5. Links:1.6km (0.99mi) atKuala Lumpur-Seremban
ExpresswayLinks: City Centre near Kg. Pandan Roundabout KL-Seremban
Expressway nearSungai Besi Airport
Zero Water Level Condition (Mode I)
Medium Flood Condition (Mode II)
Heavy Flood Condition (Mode III)
Tunnel Boring Machines (TBM)Nowadays, tunnel is one of structure
that gives many benefits to mankind. It is an underground or
underwater structure that gives human a road access through
underground or even underwater. How was tunnel built? Tunnel is
built by using a machine called Tunnel Boring Machines or mostly
abbreviated as TBM. What is TBM? How does it work? This article
will bring us to disscuss about this machine further.
The picture above shows the appearance of a TBM. It is
cylindrical in shape so the tunnel that was excavated using this
machine will also have a cylindrical shape (circular in the cross
section), that was the signature of a tunnel that was excavated
using TBM. TBM can also excavate through a variety of soil and rock
strata. It can also bore through anything from hard rock to sand.
Tunnels diameter that can be created with this machine vary from a
metre (usually bored using micro-TBM) up to 19,25 m. TBMs have the
advantages of limiting the disturbance to the surrounding ground
and producing a smooth tunnel wall. This significantly reduces the
cost of lining the tunnel, and makes them suitable to use in
heavily urbanized areas. The major disadvantage is the upfront
cost. TBMs are expensive to construct, and can be difficult to
transport. However, as modern tunnels become longer, the cost of
tunnel boring machines versus drill and blast is actually less,
this is because tunneling with TBMs is much more efficient and
results in a shorter project.Modern TBMs typically consist of the
rotating cutting wheel, called a cutter head, followed by a main
bearing, a thrust system and trailing support mechanisms. The type
of machine used depends on the particular geology of the project,
the amount of ground water present and other factors.
The above picture shows the part of a TBM that consists of
cutterhead, concrete panels, trailing gear, conveyor belt and
tunnel shield. The function of each part is :1. Cutterhead is the
machines front end part. It is called as cutterhead for reason, it
has dozens of theeth that chip away the ground as it rotates. The
machine will dig an average of 35 feet per day. At the end of its
journey, the cutterhead will have rotated the equivalent of 2.300
miles, it is enough to spin from Seattle to New York. Cutterhead
tools vary based on the ground that is excavated.2. Concrete Panels
are the the part that is installed behind the shield to form rings
that serve as the tunnels exterior walls. Ring by ring, the machine
pushes forward while the tunnel takes shape in its wake.3.
Trailling gear is the support gear that will trail behind the
machine. It includes anything that the crew and the machine itself
needs, from supply like grouts and grease to amenities like
restrooms and also kitchen. About 25 crew will be working in the
machine at any given time.4. Tunnel Shield is the protective
barrier between the ground and the workers and equipment inside the
machine.5. The last part is conveyor belt that will move excavated
soil from the front of the machine out of the tunnel to barges
waiting at nearby terminal. The belt will get longer as the machine
progresses, eventually reaching 9.000 feet in length.There are two
types of TBM, the first one is shielded TBM and the second one is
an open TBM. The usage of each type depends on what type of soil or
rock that will be excavated using this machine. There are two types
of soil that is most likely to be excavated using TBM in general,
those types are Hard Rock and Soft Ground, so depends on these
classification, the TBM is classified into Hard Rock TBMs and Soft
Ground TBMs.
1. Hard Rock TBMsIn hard rock, either shielded or open-type TBMs
can be used. All types of hard rock TBMs excavate rock using disc
cutters mounted in the cutter head. The disc cutters create
compressive stress fractures in the rock, causing it to chip away
from the rock in front of the machine, called the tunnel face. The
excavated rock, known as muck, is transferred through openings in
the cutter head to a belt conveyor, where it runs through the
machine to a system of conveyors or muck cars for removal from the
tunnel.
Open-type TBMs have no shield, leaving the area behind the
cutter head open for rock support. To advance, the machine uses a
gripper system that pushes against the side walls of the tunnel.
Not all machines can be continuously steered while gripper shoes
push on the side-walls, as in the case of a Wirth machine which
will only steer while ungripped. The machine will then push forward
off the grippers gaining thrust. At the end of a stroke, the rear
legs of the machine are lowered, the grippers and propel cylinders
are retracted. The retraction of the propel cylinders repositions
the gripper assembly for the next boring cycle. The grippers are
extended, the rear legs lifted, and boring begins again. The
open-type, or Main Beam, TBM does not install concrete segments
behind it as other machines do. Instead, the rock is held up using
ground support methods such as ring beams, rock bolts, shotcrete,
steel straps, Ring steel (Pat 2011) and wire mesh (Stack,
1995).
In fractured rock, shielded hard rock TBMs can be used, which
erect concrete segments to support unstable tunnel walls behind the
machine. Double Shield TBMs have two modes; in stable ground they
can grip against the tunnel walls to advance. In unstable,
fractured ground, the thrust is shifted to thrust cylinders that
push off against the tunnel segments behind the machine. This keeps
the significant thrust forces from impacting fragile tunnel walls.
Single Shield TBMs operate in the same way, but are used only in
fractured ground, as they can only push off against the concrete
segments (Stack, 1995).
2. Soft Soil TBMsIn soft ground, there are three main types of
TBMs : Earth Pressure Balance Machines (EPB), Slurry Shield (SS)
and open-face type. Both types of closed machines operate like
Single Shield TBMs, using thrust cylinders to advance forward by
pushing off against concrete segments. Earth Pressure Balance
Machines are used in soft ground with less than 7 bar of pressure.
The cutter head does not use disc cutters only, but instead a
combination of tungsten carbide cutting bits, carbide disc cutters,
and/or hard rock disc cutters. The EPB gets its name because it is
capable of holding up soft ground by maintaining a balance between
earth and pressure. The TBM operator and automated systems keep the
rate of soil removal equal to the rate of machine advance. Thus, a
stable environment is maintained. In addition, additives such as
bentonite, polymers and foam are injected into the ground to
further stabilize it.
In soft ground with very high water pressure and large amounts
of ground water, Slurry Shield TBMs are needed. These machines
offer a completely enclosed working environment. Soils are mixed
with bentonite slurry, which must be removed from the tunnel
through a system of slurry tubes that exit the tunnel. Large slurry
separation plants are needed on the surface for this process, which
separate the dirt from the slurry so it can be recycled back into
the tunnel.
Open face TBMs in soft ground rely on the fact that the face of
the ground being excavated will stand up with no support for a
short period of time - this makes them suitable for use in rock
types with a strength of up to 10MPa or so, and with low water
inflows. Face sizes in excess of 10 metres can be excavated in this
manner. The face is excavated using a backactor arm or cutter head
to within 150mm of the edge of the shield. The shield is jacked
forwards and cutters on the front of the shield cut the remaining
ground to the same circular shape. Ground support is provided by
use of precast concrete, or occasionally SGI (Spheroidal Graphite
Iron), segments that are bolted or supported until a full ring of
support has been erected. A final segment, called the key, is
wedge-shaped, and expands the ring until it is tight against the
circular cut of the ground left behind by cutters on the TBM
shield. Many variations of this type of TBM exist.
While the use of TBMs relieves the need for large numbers of
workers at high pressures, a caisson system is sometimes formed at
the cutting head for slurry shield TBMs. Workers entering this
space for inspection, maintenance and repair need to be medically
cleared as "fit to dive" and trained in the operation of the
locks.
SMART Tunnel and TBMPage 6