Circle Line Stage 6 - Contract 882 - Keppel Station - Singapore

Sector: Transport - Metro

Procurement Type: Construct only, Temporary works (Design and build)

Owner: Land Transport Authority

Construction Cost: Info not available 

NOMA´s client: Leighton Asia 

Design Period: From 2017

Construction Period: 2017 - 2023

Projekt Phase: Tender Design

 

The Project

The project forms part of the Circle Line Stage 6 (CCL6), which is a fully underground MRT system. The 4km CCL6 will have three stations and will close the loop for the CCL by connecting Harbourfront Station to Marina Bay Station.

Contract 882 includes the construction of Keppel Station, which is located near Keppel Distripark with twin bored tunnels connecting the station to the existing Harbourfront station in the West. Another stretch of twin bored tunnels connect a cut-and-cover tunnel at the Eastern side of Keppel Station to Cantonment Station. The contract also includes two cross passages of around 50m and 30m long respectively, linkway underpass, underpinning of Keppel Viaduct and box culvert diversion.

Key Aspects of the Project

• Station and entrances constructed using top-down construction, with earth retaining system consisting of diaphragm walls with struts
• Linkway underpass construction using steel pipe pile roof system with steel frame stiffener and soil strengthening where a relatively softer ground is encountered
• Cutting of existing piles supporting two piers of Keppel Viaduct to allow bored tunnelling beneath the piers; and underpinning of the piers by micropiles and transfer beams, with alive traffic on the viaduct
• Diversion, demolition and reconstruction of existing drainage while ensuring continuous flow of water  at all construction stages
• Complex interaction between temporary structures for drainage diversion and those for the main station excavation
• Various types of ground improvement are adopted in several parts of the project to comply with performance criteria
• Construction impact on the surrounding structures and services is to be minimised and a comprehensive instrumentation scheme is to be adopted
  
• Geology of the project typically consists of fill layer (partially reclamation fill) underlain by Kallang Formation and old alluvium soils, with thick layers of soft Kallang Formation soils encountered in the Eastern side of the station.

Scope of Works

NOMA Consulting was engaged by Leighton Asia to lead the tender design of the following aspects:

• Design of temporary retaining system for entrances excavation
• Review of strutting system for the main station excavation
• Design of temporary works for bored tunnelling
• Design of segments for temporary load cases (thrust, handling, stacking)
• Design of TMB face pressure requirements
• Design of primary support for cross passage excavation
• Design of temporary opening support requirements for cross passages
• Design of linkway underpass excavation, including steel pipe pile roof, steel frame, and soil strengthening
• Design and optimisation of Keppel Viaduct underpinning
• Design of drainage and traffic diversion
• Design of temporary works for triple cell box culvert diversion
• Recommendation of ground improvement scheme to be used in the project
• Damage assessment of surrounding structures due to tunnelling and excavations