Organised by the IOM3 Hong Kong Branch, visit to the XRL Contract 824 – Ngau Tam Mei to Tai Kong Po Tunnels was held on 18 April 2015 with the participation of 13 persons.
Before the visit commenced, a presentation of the project background was given to the participants by Mr Tresca Lai (Senior Construction Engineer) and Mr Keith Cheng (Construction Engineer) from MTR Corporation and Mr. Russell Lang (Project Director) from the Contractor of XRL Contract 824, Kier-Kaden-OSSA Joint Venture (KKOJV).
The 26-km Hong Kong section of the Guangzhou–Shenzhen–Hong Kong Express Rail Link runs from the terminus in West Kowloon to Shenzhen. The XRL tunnels are being built in underground dedicated railway tunnels. The XRL would be part of the National High-speed Rail Network, targeting to run at a design speed of over 200 km/hr, connecting to other major cities in the Mainland China. The XRL tunnels are constructed by drill and blast methods or by tunnel boring, while the terminus as well as some facilities would be constructed by cut-and-cover method.
XRL Contract 824 is one of the XRL tunnel contracts, runs beneath the natural terrain of Lam Tsuen Country Park between Ngau Tam Mei in the north and Tai Kong Po in the south. Drill-and-blast method has been adopted for excavation of approximately 2.6 km tunnel and the rock nature is mainly volcanic tuff.
A temporary circular shaft has been constructed at Tai Kong Po for mucking out and material delivery. Two permanent shafts are subsequently constructed at both ends of the tunnels. The majority of the length of the Running Tunnels would be twin bore single track tunnels. These tunnels would have an internal span of 7.8 m and an internal height of 7.6 m. The XRL Contract 824 required constructing the Crossover Cavern with an internal span of 22.2 m (resulting in an external span of circa 25 m), an internal height of 15.0 m and a length of 115 m. The cavern is 25 m away from the Ngau Tam Mei Shaft. The cavern requires to be ventilated and the existing design requires the construction of twin, Single Track Running Tunnels with Overhead Ventilation Duct between the Ngau Tam Mei Shaft and the cavern to facilitate this. These tunnels are tall and as a consequence of the track offset distance, they need to have very flat sides. With this tall slender shape the central pillar between the twin tunnels is 3.5 - 5.0 m from the outside of the temporary lining. This XRL Contract 824 also includes the construction of ventilation building at Ngau Tam Mei and an emergency access point at Tai Kong Po.
Through this visit, participants had a better understanding of the tunnel construction works and the challenges in excavation and permanent lining construction in particular the construction methodology of the large Crossover Cavern.
On behalf of the IOM3 HK Branch, we would like to express our sincere thanks to Mr Tresca Lai of MTR Corporation and Mr Russell Lang of KKOJV for the kind arrangements of the site visit.
Author: Tim Leung, Hong Kong Branch, 18 April 2015
Participants inside the Crossover Cavern of the XRL 824 tunnels
Participants inside the XRL 824 tunnels
Mr Tim Leung (L), Co-Opted Council Member, presented appreciation certificate to Mr Russell Lang (middle), Project Director of KKOJV, and Mr Tresca Lai (R), Senior Construction Engineer of MTR Corporation.
Mr Kelvin Choi (L), Council Member, presented souvenirs to Mr Russell Lang (middle), Project Director of KKOJV, and Mr Tresca Lai (R), Senior Construction Engineer of MTR Corporation