Adelaide Desalination project - Marine Tunnels and Intake and Outfall Risers
Following my role as Design manager of the marine structures I was requested to fulfil the site role as the Designer's Representative. The onsite role was extended from the marine tunnels and risers to include the pump house cavern and linking construction shafts. These shafts provided construction of the connections between the intake and outfall tunnels to the pump station and return water energy recovery turbine rooms from the desalination process.
Sydney Desalination Project - Marine Tunnels and Intake/Outlet Risers
In this project I conducted the design management for the tunnels and marine structures on behalf of the construction contractor. This role required that the design and the implementation of the documented design was delivered in accordance with the project requirements. The scope of my duties included the management of the design of the following;
- Product water pretressed holding tank
- Intake water and return flows pump station
- Intake and outfall tunnels
- Intake and outfall risers and sea floor structures.
The project had two tunnels constructed by the TBM method with a segmental fibre reinforced concrete lining.
From IEAust webpage released from Sydney Water publication.
EastLink Motorway - Mullum Mullum Creek Tunnel
The tunnel component of the project was a 1.5km, three lane twin tube tunnel. The method of construction was a combination of roadheader and drill and blast. The project role also required the design management of two ventilation building structures at each portal of the tunnel. Duties also included the management of the tunnel Design Engineering Consultant,coordination with the mechanical and electrical services contractor and the tunnel construction team.
Ringwood portal structure. The ventilation building and ventilation stack is shown.
The Melba (westbound) Tunnel
Mass Transit Rail Corporation, Quarry Bay Relief Project (North Point Plant Building)
This project covered the design of the Ventilation and Plant Structure for the new platform and tunnel structures at the North Point Station in Hong Kong. The structure has over 40 metres of its height below ground in a very densely occupied part of Hong Kong.
The plant building was sunk in a box cut which was linked to the running line. The running line was constructed using a TBM and as the machine and trailing gear needed to pass through the plant room box an early section of the plant room and running line was constructed to support the TBM. It is this section
The construction of a deep excavation in the highly populated North point area in Hong Kong required special measures for access and noise control. The close proximity of the residential apartment buildings required that not only was the excavation covered with a noise enclosure but that the excavation was to use low vibration methods. The picture at left shows the noise control building and the very close nature of the adjacent apartment buildings.
The Western Harbour Crossing, Hong Kong
This project, as one of the Airport Core Projects was central to the construction and operation of the new Hong Kong international airport at Chek Lap Kok. The total value of the project in 1993 was HK$7.4 billion with the scope of works under my responsibility being the tunnel elements, extending from portal to portal. The value of this section was approximately HK$4.3 billion. The project was extremely complex as it was designed for a joint venture of two separate contractors who chose different construction techniques within their project scope that required correspondingly different design solutions. The actual project components were open ramps and portals, cut and cover tunnels, ventilation structures and the tunnel under Victoria Harbour constructed by the immersed tunnel construction technique.
The cut and cover tunnels utilised both top down and bottom up construction in rather difficult ground conditions, being a recent reclamation on one side of the harbour and a uncontrolled fill site on the other. As a consequence of these varied foundation support conditions each landfall required a unique structural design and a construction sequence to be devised that was compatible with the changing load history from construction through to the full service life of the tunnel structures. The tunnel configuration was dual three lane with wide hard shoulders. The alignment for the approach tunnels on the Sai Ying Pun landfall was a tight spiral and the width of the excavation was therefore increased to provide the necessary sight line for the 70km/h design speeds. Consequently, the excavation was more than 40 metres wide in certain locations. The design of such tunnels required some innovative design features such as the introduction of a longitudinal hinge in the West Kowloon Reclamation tunnel to control the build up of stress in the structure as the supporting foundation material experienced settlement due to the consolidation of the new reclamation. The cut and cover tunnels, as stated previously, varied in construction, with one side of the harbour using the diaphragm walls as both the temporary and permanent structure, while the other side used a construction method where the tunnel was cast as a separate box and the diaphragm walls provided only a temporary support.
The Western Harbour Crossing Project also involved the design of an immersed tunnel. The immersed tunnel features a specialised method of construction which uses a unique structural design enabling the tunnel to be prefabricated and then transported and placed at the final location. To enable the elements to be transported they rely on their buoyancy to enable them to be towed to the tunnel site and then lowered into their final location. The elements are placed sequentially an joined forming the tunnel structure. The Hong Kong Western Harbour Crossing was then the largest immersed tunnel constructed in Southeast Asia.
The cut and cover tunnels utilised both top down and bottom up construction in rather difficult ground conditions, being a recent reclamation on one side of the harbour and a uncontrolled fill site on the other. As a consequence of these varied foundation support conditions each landfall required a unique structural design and a construction sequence to be devised that was compatible with the changing load history from construction through to the full service life of the tunnel structures. The tunnel configuration was dual three lane with wide hard shoulders. The alignment for the approach tunnels on the Sai Ying Pun landfall was a tight spiral and the width of the excavation was therefore increased to provide the necessary sight line for the 70km/h design speeds. Consequently, the excavation was more than 40 metres wide in certain locations. The design of such tunnels required some innovative design features such as the introduction of a longitudinal hinge in the West Kowloon Reclamation tunnel to control the build up of stress in the structure as the supporting foundation material experienced settlement due to the consolidation of the new reclamation. The cut and cover tunnels, as stated previously, varied in construction, with one side of the harbour using the diaphragm walls as both the temporary and permanent structure, while the other side used a construction method where the tunnel was cast as a separate box and the diaphragm walls provided only a temporary support.
The Western Harbour Crossing Project also involved the design of an immersed tunnel. The immersed tunnel features a specialised method of construction which uses a unique structural design enabling the tunnel to be prefabricated and then transported and placed at the final location. To enable the elements to be transported they rely on their buoyancy to enable them to be towed to the tunnel site and then lowered into their final location. The elements are placed sequentially an joined forming the tunnel structure. The Hong Kong Western Harbour Crossing was then the largest immersed tunnel constructed in Southeast Asia.
The first group of four elements in the casting basin at Shek-O being made ready for transport to the fitting out mooring at Junk Bay. One element has been submerged to test the watertight bulkheads. The other floating elements display the low height of freeboard.