At Tuen Mun – Chek Lap Kok, Hong Kong, the ventilation shaft is coming out into the open. The excavation work – which has been carried out to a depth of about 35m so far – is gradually revealing a circular pit built using diaphragm wall techniques.
The wall is 60m in diameter and consists of 72 panels – each of whom is 2.5m-long and 1.5m-thick – excavated up to the noteworthy depth of 67m.
The ventilation shaft is part of the TMCLK Northern Connection scheme, which involves the construction of two 5km-long sub-sea tunnels running from the western New Territories to the HK Boundary Crossing Facilities. The tunnels are currently being excavated by two Tunnel Boring Machines (TBMs), including the largest in the World (17.6m in diameter).
The ventilation shaft will be used to reduce the size of one of the TBMs’ cutter heads during the excavation of the tunnels. To allow the machines’ break-in, some panels have been reinforced using fiberglass instead of steel. The lifting and installation of the GFRP cages – which were up to 30m-long – has been one of the most challenging features of the project. After the completion of the tunnelling work, the shaft will become part of the foundation system of the proposed ventilation building.
Intrafor carried out the construction works from November 2014 to March 2015. The project team was also in charge of building the TBMs’ launch shaft – consisting of a three-cell diaphragm wall – and carrying out vibro compaction and jet grouting works along the tunnels’ alignment.
Intrafor is busily at work on both sides of Victoria Harbour, Hong Kong, as part of MTR Shatin to Central link scheme. On the northern side of the harbour, Intrafor is nearing completion of a 282-panel diaphragm wall; this structure will be part of a tunnel to be built underneath the podium of the existing Hung Hom station, one of the most important intersections of SCL. On the southern side, Intrafor has begun the construction of a launch shaft and a slurry replacement plug and lean-mix concrete wall for tunnel boring machine works. In the next few months, the project team will start constructing a shaft for the southern ventilation building and another TBM’s launch shaft with a multi-cell “peanut” shape. Both the shafts will be built using diaphragm wall techniques.
The world’s largest TBM (Tunnel Boring Machine) will be operative soon at Tuen Mun – Chek Lap Kok Northern Connection site. This equipment will be used alongside a smaller TBM to build two sub-sea tunnels that will connect Tuen Mun, in the New Territories, to the Hong Kong Boundary Crossing Facilities (HKBCF) as part of the extensive Hong Kong – Zhuhai – Macao scheme. Intrafor has set the stage for this project constructing the diaphragm walls of the tunnels’ launching and ventilation shafts and performing deep compaction and jet grouting works. The construction of the three-cell launching shaft involved many challenging features, including the installation of four T-panels to absorb the ground compression and of some fiberglass panels to allow the TBMs’ breakthrough. Works were performed on a fresh reclamation within a tight schedule. The beginning of the excavation of the two tunnels is scheduled at the end of March 2015.
Directional coring work for the Tseung Kwan O to Lam Tin Tunnel ground investigation is nearing completion. The work is part of a broad ground investigation undertaken by Intrafor for the Hong Kong Civil Engineering and Development Department and includes land and marine drilling, geo-hazard surface mapping, contamination investigation and a range of specialist in-situ geotechnical tests. Directional coring is being undertaken at two locations through regional geology comprising granite and tuff. The longest core hole is 780m and, for the 600m completed to date, the drilling team has consistently delivered high quality continuous core using Intrafor’s in-house designed steerable core barrel for the curved sections of hole. Due to the ability of directional coring to follow the planned path of the 2.6km tunnel, the field data will add significant value to the ground model developed for the final design.
As part of the Hong Kong Link Road 03 (HKLR 03) contract, Intrafor is going to start constructing canopy pipes underneath the Airport Express Railway (AEL), the railroad connecting the airport to Hong Kong Island. This stage of the project includes the drilling and the grouting of 44 steel-casing pipes (813mm OD). This pipe roofing system will stabilise the ground, avoid the settlement and protect the workers during the box jacking and the excavation of the tunnels passing under the existing railway. Its construction will be performed using two tailor-made Front-Steer drilling rigs suitable for mixed ground conditions (rock and soil), developed in collaboration with two international suppliers. Works will begin in April 2015 and will last for six months.
Intrafor has just launched the works of the South Ventilation Building to Admiralty Tunnels site in Hong Kong (SCL 1128) as part of the Shatin to Central Link scheme. This project, commissioned by MTR Corporation, aims to the extension of the railway network connecting the New Territories and Kowloon to HK Island. Intrafor will execute the construction of two launch shafts for the excavation of four new underground tunnels and of one shaft for a new ventilation building. The three shafts will be constructed using diaphragm wall techniques. Intrafor will also execute ground improvement treatments – including TAM (Tubes à manchettes), jet grouting and compensation grouting – along the tunnels’ alignment.
VSL-Intrafor recently completed a 6km cut-off wall necessary for the construction of Doha’s new container port. Built 22m underground, the cut-off wall was constructed using VSL-Intrafor’s BC40 Cutter equipment and special plastic concrete mix. This innovative concrete mix was essential to the wall’s construction, as it will later be destroyed to let sea water in and welcome container ships into the port.
Intrafor is building a 34,000m2 diaphragm wall under the existing Hung Hom station and the Hong Kong Coliseum. This critical contract is being executed without disruption to the existing Hung Hom station and in very low headroom. Excavation is carried out using mini-cutters and special low-headroom grabs with boom and grab length reduced to the minimum. Cranes had to be modified to move equipment and reinforcement cages.
Participating in Macau’s expansion and the development of the Cotai area, Intrafor was awarded a project for the construction of the basement retaining wall for a new hotel and casino. The 560m-long diaphragm wall will be built 40m deep into old reclaimed land and house part of a luxury hotel and casino featuring up to 700 gambling tables and 1,000 slot machines.
After successfully completing the original cut-off wall scope of 52,500m2 on the New Port Project in Qatar, VSL-Intrafor were awarded additional works comprising the construction of an additional 55,530m2 of cut-off wall over a plan length of 3,210m, including geotechnical investigation works. The cut-off wall is being constructed using VSL-Intrafor’s BC40 Cutter equipment and a special plastic concrete mix; excavation works for the wall are being carried out to depths of up to 22m below existing ground level. The cut-off wall reduces the horizontal flow of water through the subsoil and fractured limestone, facilitating the safe and economical dewatering and dry bulk excavation works in the port’s access channel.
Leighton awarded Intrafor a contract for a MTR interchange station, part of the new 17km long Sha Tin to Central Link metro line project. Located under the podium structure of the existing Hung Hom station, the works comprise 1075lm of 1.2m thick diaphragm wall and barrettes ranging from 20m to 60m in depth, representing a total of 40,000m³ of excavation. 5 slurry walls totaling another 3,400m³ of excavation are also part of Intrafor’s scope. The main challenge is to work under a very low headroom of 5.5m. Excavation is carried out using minicutters and special low-headroom grabs with boom and grab length reduced to the minimum. Cranes had to be modified and a special gantry system had to be developed to move equipment and reinforcement cages.
Intrafor adopts reusable steel formwork as much as possible. However, it is still necessary to use wood for some applications, such as to cover starter bars in diaphragm wall panels. To reduce the environmental impact, Intrafor is now using 100% FSC-compliant wood, where available, for this purpose. The FSC (Forest Stewardship Council) identifies and certifies forests that are well managed and where biodiversity, productivity and the ecology are maintained.
Intrafor Hong Kong introduced a new cutting wheel system known as ‘Roller bits’ for the construction of diaphragm walls in steep and hard rock. Construction work including 144m of diaphragm walls was needed for Intrafor to deliver the 15m-deep sealed basement, ready for construction of the building above.
Intrafor has successfully completed a high-proﬁle project in central Hong Kong opposite the new IFC tower and shopping complex. Work involved the installation of 530m of diaphragm wall and 22 barrettes in a very constrained area. Special covers were manufactured for the bentonite storage pools to improve the site’s visual impact.
Intrafor is carrying out a pioneering contract to install the first friction grouted barrette piles in Hong Kong’s ‘marble zone’. The 65 barrettes are for housing in Yuen Long. More than 4,500t of concrete and steel kentledge imparted a 3,300t load to each barrette during the testing. Less than 20mm settlement compared with the 66mm design limit.
VSL Intrafor has helped Perth City Link Rail Alliance reach a major project milestone. Completion of more than 84% of diaphragm walling and 60% of micro-piles puts the Alliance in an excellent position to slew the rail line, a critical step for finishing the work.
VSL is undertaking ground engineering works for the Perth City Link project, which will reconnect two districts that were separated by railway lines. VSL in Australia and Intrafor are in joint venture with local piling contractor Avopiling.
Intrafor has won its third contract on the Guangzhou-Shenzhen-Hong Kong Express Rail Link. The latest contract involves the construction of diaphragm walls for a cut and cover tunnel on the 26km-long Hong Kong section. The diaphragm wall has a total volume of 13,000m³. The joint venture main contractor was Maeda and China State.
INTRAFOR has recently been awarded a contract for the construction of the Diamond Hill Station of the Shatin-Central Link (SCL) MTRC project in Hong Kong. The Shatin- Central Link will provide a direct connection between the stations on the border with Guangzhou Province of PRC and Admiralty Station of Hong Kong. INTRAFOR scope of works will include the construction of 20,000m2 of permanent Diaphragm Walls and barrettes together with the associated toe grouting, shear pins and pumping tests. The mobilization of three trench cutters will be required to complete the Diamond Hill station in 15 months.
Intrafor has been awarded a contract by Ove Arup & Partners to install friction barrettes for a public housing development in Hong Kong where the piles are being installed in a marble-zone area. (65 friction barrettes and four 3,100t loading tests).
The Entasis-Intrafor Consortium has built 1.5m-thick diaphragm walls to depths of 55m for the West Kowloon Terminus approach tunnel (south) as part of Hong Kong’s Express Rail Link. Work also includes the installation of shear pins, fissure grouting and the removal of an existing breakwater.
Intrafor have been awarded the cut-off wall contract for the New Port Project in Qatar. Included in Intrafor’s scope is the construction of 3,150m of cut-off wall; geotechnical investigation works and providing specialist plastic concrete. Using the Intrafor BC40 Cutter equipment, Intrafor will construct over 51,000m2 of cut-off wall to depths of up to 22m below existing ground level.
Construction of a two-storey basement in Sheung Shui in Hong Kong brought considerable challenges as the adjacent three-storey buildings stood on shallow friction concrete piles and pad footings. Intrafor’s careful choice of methods and equipment avoided any disturbance or settlement of the surrounding buildings.
Intrafor has taken just four months to build a 1.2m-thick diaphragm wall with a total volume 24,000m³ and a depth reaching 60m below sea level in Hong Kong. The design and construct project was for the basement of a new residential development in Tseung Kwan O for leading property developer Sung Hung Kai.
Intrafor has completed its deepest ever shaft, finishing four months ahead of schedule. The 91m shaft is part of Hong Kong’s Harbour Area Treatment Scheme. Intrafor developed patented sacrificial void formers for the project. Achieved tolerances on verticality were extremely low, well within requirements, and the jointing between the panels was made with high quality, thus avoiding the need for expensive and time consuming concrete finishing or trimming.
Intrafor has entered the ground improvement market in the Middle East. Successful trials of equipment from Dutch manufacturer ICE led to an order for four vibroflots. Commissioning in June was followed immediately by the award of Intrafor’s first contract to use the equipment. The project is for stone columns at a sports facility in the royal palace grounds in Abu Dhabi.
Intrafor is working on a 21,000m³ diaphragm wall project: the Central Wanchai Bypass Central Interchange. Challenges include busy traffic, buried seawalls and low headroom, for which Intrafor has developed a special rig. A BC40 cutter and two excavation cranes have been mobilised for the project.
Intrafor has secured a major contract to construct one of the most challenging sections of the MTR’s new Express Rail Link (XRL), a part of Contract 820. The section passes under a densely populated and heavily piled area. Intrafor’s responsibilities encompass foundations, ground treatment and diaphragm wall shaft work.
Use of a new patented “soft milled joint” developed by Intrafor has avoided the need for extensive concrete cutting between panels on a 91m-deep diaphragm wall shaft on Hong Kong’s HATS project. The shaft diameter of just 12.3m makes the excavation works challenging. Trapezoidal blocks made of lightweight precast concrete replace the same volume of hard concrete.
Intrafor new proprietary directional core barrel was used on its first project. Maeda-Crec-Seli JV awarded Intrafor the contract for ground investigation along a drainage tunnel. The new barrel developed in 2009 was used for a 160m-long hole with two horizontal curves. Rock fissure grouting was then carried out to treat a known fault zone.
A new Klemm 702-2 rig installed 16 micro-piles for an elevator inside Abu Dhabi’s Presidential Palace. It was the only one in the UAE that could gain access without extensive demolition. In Hong Kong, acquisition of a third trench cutter, a Bauer MC64/BC40 used on the Express Rail Link, that enhances Intrafor’s position as a leader in special foundations.
Intrafor’s work on Hong Kong’s Central Reclamation Project includes a wall with a very challenging design requiring unusual reinforcement logistics. Conventional lapping of the bar was impossible, the solution was to lift and place the 55t, 38m-long cages as single sections using a three-crane multiple lift.
The works Intrafor carried out on behalf of LAM Geotechnics involve drilling one vertical and one inclined hole to obtain geological and geotechnical information for the design of a traffic tunnel in Hong Kong. Intrafor is drilling 315m down to the invert level of the future traffic tunnel.
Two Intrafor diaphragm wall shafts for Hong Kong’s harbour area treatment scheme are well under way, including one by cutter in Sai Yin Pun where the rockhead depth is 91m. The 12.3-diameter shaft should be the deepest diaphragm wall ever built which will be exposed over its full height, as bulk excavation will proceed in rock down to 150m.
Intrafor won the subcontract for the diaphragm walling and barrettes of an underground tunnel of Hong Kong’s Central Reclamation project. The work comprises 1km of 1. 2m-thick diaphragm walls to be constructed into the granite bedrock and around 107 1. 2m barrette piles for foundations to the tunnels.
With 39m, the bulk excavation at Cairo’s Metro’s Attaba Station is one of the deepest of its kind ever built with a non-circular diaphragm wall and strutting. Intrafor successfully completed two 1,500mm-thick diaphragm walls that are 85m-90m deep. The total amount of diaphragm walls was 61,000m².
Intrafor has excavated a major shaft for the Drainage Services Department of Hong Kong. The 58. 5m-deep shaft has a 12m internal diameter with a 1. 5m-thick wall and includes a slurry wall, which is 84m long, 1m thick and 30m deep. This is the deepest stop end installed by Intrafor to date.
Intrafor Hong Kong has just been awarded a Horizontal Directional Drilling (HDD) contract for the Government of the Hong Kong S.A.R. (Drainage Services Department). The works will include the directional drilling of two holes located near two small villages in Lamma Island (South West of Hong Kong Island), as well as the installation of HDPE pipes in those holes, for the construction of two submarine outfalls from a sewage treatment plant. The works are due to start in December 2010.
Intrafor Hong Kong has signed a contract with Karlin Consultants, a local developer, to design and construct the cofferdam of a new commercial development in Fanling, located in the New Territories of Hong Kong. The works will include the construction of bored piles and an L-shape diaphragm wall around a 1,300m2 land plot. Intrafor will also carry-out the excavation works and installation of the temporary strutting system and finally construct a 3,000m3 pile cap.