leighton lr

200 | Sandvik Year 2012 in Action

to Mainland China

HonG KonGS HiGH SpEED rAil linK

Sandvik DT1230i and DT1330i in operation at XRL 822 project.

ARtIClE by: GEORGE dEMEtRI

As FIRst publIshEd IN

wORld tuNNElING, JAN/FEb 2013

TUNNELING AND UNDERGROUND CIVIL ENGINEERINGTUNNELING AND UNDERGROUND CIVIL ENGINEERING


HonG KonG

Hong Kongs improving transport links with mainland China include the XRL high speed rail tunnels currently under construction. George Demetri visited the longest drill and blast section underway in Hong Kong.

he Hong Kong section of the Guangzhou-Shenzhen-Hong Kong Express Rail Link (Express Rail

Link, XRL) is a high speed line that will link Hong Kong to Panyu, Guangzhou and Guangdong in the north. In reinforcing social and economic ties between the two regions, the project is of vital importance to Hong Kong and will strengthen its status as the southern gateway to China.

With operating speeds of around 200km/hr along the Hong Kong section (and up to 350 km/hr on the overland sec-tion further north), the travel time between Hong Kong and Futian at the Shenzhen boundary will be around 14 minutes, and 48 minutes to Guangzhou South.

Currently under construction, the US$8 billion Hong Kong section will comprise 26km of tunnel and a terminus station in West Kowloon and will connect to a 116 km northern section including four inter-mediate stations which commenced in 2009 ahead of the Hong Kong section. With the West Kowloon terminus, there will be no

T intermediate stations in the HKSAR. Completion is scheduled for 2015.historyIn 2000, the government of the Hong Kong Special Administrative Region (HKSAR) proposed a Regional Express Line as envis-aged in its Railway Development Strategy; this later became the Hong Kong section of the Guangzhou-Shenzhen-Hong Kong Express Rail Link (Express Rail Link).

In April 2008, Hong Kongs MTR Corpora-tion Limited (MTR) was commissioned by the HKSAR government to carry out further

with operating speeds of around

200 km/h along the hong Kong

section and up to 350 km/h on the

overland section further North the

travel time between hong Kong and

Futian at the shenzhen boundary will be

around 14 minutes, and 48 minutes to

Guangzhou south.

Construction projects around the world | 201

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planning and design of the XRL project; the project was later put out for public consul-tation. In October 2009, the scheme and its amendments were authorised, funding approved by the Finance Committee of the Legislative Council in January 2010, and construction begun later that month.

AlignmentIn determining the route of the tunnel alignment, MTR has taken numerous factors into account, including techni-

cal, geotechnical, operational and safety aspects, land requirements, effects on the community and environment, and the over-riding programme constraints to connect with the northern section.

The major consideration in the urban area of Hong Kong, particularly around the West Kowloon terminus, was to minimise construction and operational impacts on the local community and infrastructure, particularly road capacity for deliveries and

Kim Bailey, Plant Manager with Leighton Contractors (Asia) Limited at XRL 822 project


TUNNELING AND UNDERGROUND CIVIL ENGINEERING

disposal of excavated material. In urban West Kowloon, the alignment runs beneath two major roads (Sham Mong Road and Hoi Wang Road) in reclaimed land. Continuing northwards, the alignment passes under the Tai Mo Shan mountain range into the New Territories, Hong Kongs rural hinterland area, before finally crossing the estuarine marshland of Mai Po, that forms the HKSAR boundary.

The project also includes eight emergency access points (of which seven are also venti-lation buildings), stabling sidings for trains and an emergency rescue facility at Shek Kong in the rural section. The at-grade sidings, located around half way along the alignment, provide the primary emergency access point for effective response to inci-dents inside the tunnels.

backgroundMTR has packaged the construction con-tracts primarily in consideration of geol-ogy, tunnel profile, length and accessibility. Among the major civil contracts for tun-nels, three contracts are being constructed by drill and blast, three by tunnel boring machines (TBM), and one by a combi-nation of TBM and cut and cover excavation.

The section being constructed by Leighton Contractors (Asia) Limited (Leighton) is the longest single drill and blast section, comprising 7.6km of excavation extending from Tse Uk Tsuen to Shek Yam (contract 822).

Leighton was awarded the US$434 million contract in March 2010 and expects to achieve breakthrough in late 2013, with completion of the lining scheduled for 2014. Having completed

the civil works contract, Leighton will hand over to other contractors to carry out the fit-out and track work.

profilesThe project provides a twin track, drained, lined tunnel with a central dividing wall for the majority of its length with a pair of sin-gle track tunnels required at the northern limit. A number of different cross sections are required to satisfy operational require-ments.

The main running tunnel has a 130m2 cross-section (Type C profile, green) (8.5m x 14.2m-wide) bisected by a 354mm-thick central reinforced concrete dividing wall. However, the tunnel section increases to 180m2 (Type M profile) in the vicinity of the two ventilation building to accom-modate Leightons alternative ventilation proposal. In order to achieve a full face blast on a face up to 17m high and almost 19m wide, Leighton is using two modified Sandvik three boom DT1330i tunnelling jumbos.


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VentilationThe MTRs conforming design proposal included two separate ventilation tunnels alongside the main running tunnel with adit connections to the main tunnel at the required intervals. As part of Leightons alternative proposal, the separate ventila-tion tunnels were eliminated by incorporat-ing the ventilation requirements into an enlarged running tunnel with an integral overhead ventilation plenum (OHVD) (Diagram xxx).

Two permanent ventilation adits are locat-ed at a separation of 6.5km. The southern adit is a vertical shaft some 90m deep and therefore not suitable for the main tunnel construction access. A temporary construc-tion adit (to be back-filled on completion of the project) was therefore specified close to the southern contract limit to provide two excavation faces in order to meet the chal-lenging construction programme.

Temporary ventilation to the face is pro-vided by twin 500kW fans located at the surface with fresh air delivered at a rate of up to 200m3/s through twin 2.6m diam-eter ventilation ducts. Mitigating the noise impacts of these fans has been another challenge.

GeologyThe project was tendered on a Geotechni-cal Baseline Report (GBR) prepared by MTR that confirmed existing knowledge and MTRs experience on the West Rail DB350 tunnelling contract. With the excep-tion of some soft ground at the northern, Pat Heung portal the excavation is pre-dominantly in competent rock including Granodiorite and tuff, with some granite material. Some difficult ground conditions have been encountered in completely de-composed granite (CDG) that has required mechanical excavation at the face. In such zones, Leighton has resorted to sequen-tial excavation and support. Heading and bench or two pilot drives either side of a centre column were adopted in particularly challenging ground conditions.

Regular probe drilling is being undertaken as specified to provide a better understand-ing of the geology immediately ahead of the face and to date no significant water problems have been encountered.

liningIn good competent rock, the majority of the lining is predicted to be unreinforced, although reinforcement is used in the centre dividing wall on which work will start in 2013. Shotcrete (50mm thick) is used for temporary support of the excavated profile and is either plain, or steel fibre-reinforced.

Polypropylene fibres are added in all linings at a rate of 1kg/m3 of concrete to increase resistance against spalling in the event of a fire. The concrete is then cast to 350mm thickness between a PVC sheet waterproof-ing membrane and formwork; the thickness varies at junctions, the lining can be up to a 1m-thick unreinforced lining in good competent rock.

the project provides a twin track,

drained, lined tunnel with a central

dividing wall for the majority of its

length with a pair of single track tunnels

required at the northern limit. A number

of different cross sections are required to

satisfy operational requirements.



The permanent concrete lining is cast in 12m bays, with four bays cast each week. Once the main lining has been installed, Leighton will pour the 350mm-thick invert plus filter drains, then pour the base slab for the rail track. The civil works also include the ser-vice/evacuation walkways on either side.

Excavated rock will be processed through a screening plant to provide the drainage material under the tunnel base slab. This avoids having to re-import material to com-ply with the drainage layer requirements, and it also reduces the environmental im-pacts of having to dispose of the excavated material off site.

Current statusAt the time of the authors visit to the site in mid-September 2012, Leighton was drilling and blasting two faces simultane-ously, having excavated around 1,500m from the south and 600m from the north. A third work site for the 90m deep shaft was also nearing completion of the first phase, a 30m deep basement located above the shaft.

Tunnel works also included the installation of a waterproofing membrane and perma-nent tunnel lining. Tunnelling continues 24/7 with day and night shifts, employing around 250 people/shift.

FACts

sANDVIk DX700

hole diameter 76-115mm (3-4 1/2)

Rock tools 45 or 51mm (1 3/4 or 2)

Rock drill hL710, 19,5kW

Engine

TIER 3: Caterpillar C 7, 168 kW/2 200 rpmTIER 4: Caterpillar C 7.1, 168 kW/1 800 rpm

flushing air 8,1m3/min,

up to 10bar

Dust collector23m3/min at 1000 mm vacuum h2O

Width TIER 3: 2.5mTIER 4: 2.45m

Length 7.2m / 10.7m

height 3.6m / 3.2m

Weight

TIER 3: 14 800kgTIER 4: 14 900kg


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blastingIn order to meet the demand for explosives the project also included the construction of two explosives magazines to be supplied from the government magazines. Whilst Leighton retains overall management and operational control of the two magazines the facilities are shared by the other XRL drill and blast contractors; XRL Contract 821 share So Kwun Wat magazine and XRL Contract 824 the magazine at Tai Shu Ha (Yuen Long).

leighton is using sandviks isuRE

software to manage the two 3-boom

jumbos working simultaneously on the

large faces. the software takes the

blasting parameters and tunnel size and

creates an array of holes, maintaining

the same cut pattern and allowing rings

to be added, thereby achieving a pattern

very quickly.

Kim Bailey and John Owens, Leightons Superintendent at XRL 822

project discussing with Sandvik Hong Kongs sales manager Kenny Chen.



Hong Kongs Mines Division (Mines) of the Civil Engineering and Development Department is responsible for the govern-ance of explosives material in Hong Kong. With substantial demand being placed on their staffing resources Blasting Competent Supervisors were appointed from MTR staff to help manage their responsibilities to ensure compliance with licences and permits.

Leighton is the first contractor in Hong Kong to bring in GPS tracking systems for the explosives delivery vehicles to eliminate the requirement for armed escorts.

On XRL, Leighton is using standard bulk emulsions with high strength detonator cords. Other than that, initiation systems are typical MSLP non-electric (NONEL) delays. It has also used dual-delay systems (with two detonators) which are not typical in civil tunnelling.

Use of bulk emulsion has the added advan-tage in that it does not become an explosive until sensitised by nitrogen gas. At the end of the day unused quantities of un-gassed bulk emulsion do not need to be returned to the magazine or destroyed on site as re-quired for packaged emulsions (cartridges).

Managing ground vibrations and air blast the airborne shock waves resulting from the detonation of explosives was an issue in blast design in the early stages of the project but is less of a consideration as the tunnel advances beneath Tai Mo Shan.

The large tunnel faces introduced addi-tional technical challenges to the traditional adoption of MSLP connection methods resulting in some pioneering work with dual delay systems.

Another first for the project has been Hong Kongs first-ever tunnel deck blast a blasting method where instead of a con-tinuous hole loaded with bulk explosives, the charges are segregated in the hole by crushed aggregate and fired independently on separate delays. In this way, charge weight restrictions are not exceeded, but because the charges go off milliseconds apart, they do not generate vibrational sequences, yet still allow the full 6 m ad-vance. Vibrations can therefore be managed in accordance with project requirements while still maintaining programme rates.

The 22-hour blasting cycle was adjusted to allow two blasts per day to be achieved within the window provided by the pro-jects Environmental Permit.

In order to minimise the size of the tempo-rary construction adit, and for optimum production a Sandvik underground rock breaker and crusher were installed in a dedi-cated underground cavern at the bottom of the adit (which will also require back-filling on completion), and the excavated material brought to a surface stockpile on a conveyor.

isuRELeighton is using Sandviks iSURE software to manage the two 3-boom jumbos work-ing simultaneously on the large faces. The software takes the blasting parameters and tunnel size and creates an array of holes, maintaining the same cut pattern and al-lowing rings to be added, thereby achieving a pattern very quickly. Specific additional holes can be manually added later. Typi-cally, holes are spaced around 0.7m apart. Most hole patterns seen on the project are generally constant for a given tunnel profile with a maximum of 160 holes being used on the M-profile

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FACts

sANDVIk DT1331i

Coverage 20 - 232m2

hole diameter 43 - 64mm

hole length 3 344 - 6 085 mm

Booms 3 x sB100i

feed 3 x Tf5i 12-21 ft

Rock drill 3 x RD525

Control and operation system

iDATA

Length (with default feed) 17 780mm

WidthDrilling/ Tramming/ Transportation

3 860 / 3 050 / 3 050mm

height Drilling / Tramming

5 965 / 4 965mm

Weight Standard / with utility boom

50 000 / 54 000kg

sANDVIk DT1231i

Coverage 20 - 211m2


hole length 3 344 - 6 085mm

Booms 2 x sB150i

feed 3 x Tf5i12-21ft

Rock drill 3 x RD525

Control and operation system

iDATA


Width Drilling/ Tramming/ Transportation

3 860 / 3 050 / 3 050mm

height Drilling / Tramming

4 780 / 3 780mm


45 500 / 49 500kg


Leighton uses separate software for blast analysis, detonation sequences and the allo-cation and analysis of the firing sequence of a round, as well as displaying other infor-mation required for blasting approval.

From a technical standpoint blast holes of up to 64mm could be used on faces of this size, however 48mm- or 51mm-diameter holes are being used to better manage the drilling around the perimeter. Holes at the perimeter are closer together and lightly charged to ensure that the blast conforms to the required line of the tunnel profile with minimal over or underbreak.

Holes drilled across the bottom are de-signed to break out the floor to create the next section of grade, so are spaced differ-

ently to the closer-spaced and more highly charged holes where the blast starts.

EquipmentSandvik equipment forms a key element of Leightons inventory used to excavate the tunnel. For the project, Sandvik has sup-plied:

In addition, there are 12 technicians sup-ported by Sandvik across the three sites.

The Sandvik drill rigs were chosen not only for their reach and automation, but also for their computerised sophistication which among other things, helps minimise the time and cost problems of under and overbreak. However, such sophisticated equipment requires competent drillers with several years of experience in addition to specific Sandvik training to become familiar with the equipment and software.

The demands of a project of this size requires significant power supply. At Shek Yam, at the southern limit of the project a dedicated (2MVA) substation has been constructed to meet the project require-ments for the jumbos (drilling), Charmecs (load/charge), shutter lining, shotcrete and pumps. In Pat Heung, at the northern limit of the project power was initially provided

the sandvik drill rigs were chosen not

only for their reach and automation,

but also for their computerised

sophistication which among other

things, helps minimise the time and cost

problems of under and overbreak.

2 x DT1330i 3-boom jumbo drill rigs3 x DT1230i 3-boom jumbo drill rigs2 x DT820-SC 2-boom jumbo drill rigs1 x DX700R Crawler Drill rig1 x Ranger 700 Crawler drill rig2 x rock breakers1 x UJ540 mobile crusher1 x QA140 mobile screenRock tools and bit grinding servicesAgreements for the supply of spare

parts and on-site services.



from banks of generators until such time as 3 km of HV cable could be brought in across adjoining contracts.

A 700kVA mining substation follows the tunnel advance and is moved every 200m to service the tunnel advance. Intermediate substations are being established on the tunnel wall at approximately 1km intervals to meet lighting and general power require-ments.

safetySafety is of paramount importance on all Leighton and MTR projects. The adoption of leading technology to achieve the project objectives requires skilled operatives at

all stages of the drill and blast excavation cycle and the clear transfer of responsibility from one team to the next at each consecu-tive stage. This is being achieved through the adoption of a release note system and pre-shift briefings, whereby any comments or remarks raised by the previous shift are noted on the release note and communicat-ed to the follow-on shift. Clear communica-tion is the most important safety tool on a construction site.

The tunnel environment is defined as a confined space in that it is enclosed with restricted points of entry/exit, it is at risk of restricted or poor ventilation and has the possibility of insufficient oxygen

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sANDVIk DT821-sC

Coverage 110m2


hole length Up to 6 180mm

Booms TB90

feed Tf50016ft

Rock drill RD520

Control system ThC561


Width Drilling/ Tramming/ Transportation

3 000 / 3 000 / 2 500mm


27 000 / 29 400kg


and/or harmful gases. The ambient condi-tions of high temperature, high humidity and lack of natural light are further hazards, in addition to the pre-existing conditions that define it as a confined space. A detailed risk assessment report has therefore been prepared that identifies all the hazards and proposes a raft of measures both procedural and engineering measures to reduce the risks to as low as reasonably practicable.

Prior to breakthrough of the tunnel the exit route from the tunnel could be in excess of 4km. Therefore the ability to clearly identify the location of an emergency, the ability to manage it, and ensure safe evacu-ation are issues that have been addressed in liaison with the Hong Kong Fire Services Department (FSD) who will lead any emer-gency rescue should it prove necessary.

Communications, ventilation and emergen-cy lighting are key provisions. Fire preven-tion equipment and emergency communi-cations are provided in the tunnel. Audio and visual alarms are connected to the tally room/Emergency Control Centre at the sur-face. These regular stations, situated every 60m also include a fire hydrant with 30m of hose connected to a fire main running the length of the tunnel, and fire extinguishers at each location. First aid kits are main-tained every 100m within the tunnel.

In order to facilitate evacuation and rescue procedures chainage markers are located every 50m along the tunnel wall to enable accurate location of any incident. Segregat-ed walkways are provided for regular and emergency access/egress and are advised to workers in the tally room before they enter the tunnel on each shift. Emergency lighting is provided in accordance with the specifi-cation.

Self-rescuers are made available to all tunnel workers. These are once-only use equipment that provide half an hour of respirable air, sufficient for evacuation in the event of ventilation failure and/or the presence of harmful gases. Sufficient self-rescuers are kept in storage boxes at all major work faces, and vehicles entering the tunnel will have adequate self-rescuers for the driver and all passengers. Occasional workers and visitors will be required to take a self-rescuer from the tally hut and carry it with them whilst underground and return it to the tally hut on exit.

The project site office is in regular contact with the regional fire stations keeping them appraised of tunnelling progress through regular monthly visits and a drawing show-ing the tunnel status and any other point of interest.

Going forward liaison with adjacent civil contractors to monitor programme and confirm responsibilities at the project interfaces is ongoing. Discussions have com-menced with the MTR Corporations desig-nated contractors providing the permanent way, and project wide systems, the first of which the Construction Stage Mobile Phone Network will commence in June 2013 with the others due to commence in December 2013, when excavation has been completed.

For their assistance in the preparation of this article,

World Tunnelling would like to thank at Leighton

Asia: Francis Haden, Peter Ayres, Kim Bailey,

Darren Grant and John Owers, and for his as-

sistance on site in Hong Kong, Kenny Chen, Sandvik.

Also thanks to Chan Hon To, Sandvik managing

director, Hong Kong, and Nina Lehtonen, Sandvik,

for facilitating the trip.




In order to minimise the size of the temporary

construction adit, and for optimum production a

sandvik underground rock breaker and crusher were

installed in a dedicated underground cavern at the

bottom of the adit, and the excavated material brought

to a surface stockpile on a conveyor.

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