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| Atkins’ tunnelling breakthrough on major Hong Kong scheme  The Lai Chi Kok Drainage Tunnel – a major drainage infrastructure project in Hong Kong undertaken by Drainage Services Department, HKSAR – witnessed its final TBM (tunnel boring machine) breakthrough this month, after three years of tunnelling design work by Atkins.The Lai Chi Kok Drainage Tunnel is a stormwater drainage system which will form an integral part of the overall flood control strategy for West Kowloon, Hong Kong. The new system will capture surface runoff at six locations and discharge it into Victoria Harbour to alleviate flooding of the low-lying developed areas. With the implementation of this scheme, the uphill flows will be intercepted and the overall drainage capacity in the Lai Chi Kok area will be enhanced to cater for rainfalls of a 1 in 50 years return period. The scheme is comprised of two 4.9m internal diameter tunnels (Main Tunnel and Branch Tunnel) totalling 3.7km in length, which intercept and transfer stormwater directly into the harbour. In addition, Atkins carried out the design of six intake drop shafts, two 45m-deep shafts (10m in diameter), associated temporary work of stilling basin and outfall structures, along with 270m of associated connection adits and ancillary underground works. As the tunnels are located in an urban area, Atkins had to ensure that construction did not adversely affect sensitive structures such as railways, viaducts and culverts. The design team also had to consider significantly high earth and water pressure when undertaking the structural design. To ensure the lowest possible impact to the environment, a slurry-type tunnel boring machine was selected to drive within bedrock, mixed ground and soil over 40m deep and under high underground pressure. write your comments about the article :: © 2011 Construction News :: home page |