Press-in method utilised for Singapore’s Deep Tunnel Sewerage System

The Press-in Method has been adopted for the shaft construction*1 project for Singapore’s Deep Tunnel Sewerage System (DTSS). With construction underway, this is the first project in Singapore to install HAT-type steel sheet piles using the Hard Ground Press-in Method*2. The SILENT PILER™ was purchased from GIKEN and Giken Seisakusho Asia Pte., Ltd. (Head office: Singapore, President: Atsushi Ohira) has dispatched an on-site technical instructor.

In recent years, hard ground soils are becoming more common in construction projects in Singapore. The advantage of the HAT sheet pile is its width of 900mm expediting installation time compared to other sheet piles. Additionally, the total material weight of a HAT pile can be reduced comparison to other steel types and therefore reduction in material cost. For these reasons the demand for the Hard Ground Press-in Method of HAT sheet piles is expected to grow in the Singapore market. We believe that this project will further strengthen our ability to grow the Press-in Methods market in Singapore.

※1 A construction to build a vertical passageway connecting surface and underground. The passageway will be used to install a tunnel boring machine.

※2 A method of excavating the ground directly with a pile auger interlocked to the SILENT PILER. The installation of the piles is achieved simultaneously while pile auger is pulled out.

Securing water resources is a concern in Singapore. DTSS is a system to collect and transport domestic wastewater through a deep sewerage tunnel laid underground. The collected wastewater is purified by coastal treatment plants and altered into ultra-clean, high-grade reclaimed water called "NEWater". NEWater meets drinking water quality standards and is also used as industrial water, contributing to resolving water problems.　Singapore government plans to extend the deep sewerage tunnel to serve the western part of Singapore by 2025. Upon completion, the tunnel would total 88 kilometers.

Project website: https://www.pub.gov.sg/dtss/about

■Selection Basis
As the site is located around schools, residential areas, roads and existing railway lines, avoiding vibrations and noise that would interfere with the lives of residents and surrounding infrastructure was essential. Additionally, safety concerns were expressed on the negative impact vibrations would have on road and railway operations.

The Press-in Method by the SILENT PILER enables the installation of piles without vibration and noise. As the machine grips onto installed piles, where the design and installation are carried out in the Giken prescribed manner, equipment stability is ensured and safety maintained. The Press-in Method was adopted as the only method capable of resolving the aforementioned concerns.

■Future expectations
The total land area of Singapore is small and the use of underground space is promoted in urban development. A variety of infrastructure and facilities including expressways, railways and sewage treatment facilities will be built underground in the future. Amidst these developments, GIKEN Group expects the adoption of the Hard Ground Press-in Method to continue to grow in Singapore.

■Profile of GIKEN Group
GIKEN developed the SILENT PILER, the world's first reaction-based hydraulic pile jacking machine, installing piles with no noise and vibration. GIKEN Group now actively promotes the Press-in Technology worldwide and contributes to the construction industry by proposing and implementing innovative solutions. The innovative technology of press-in provides a unique solution and the adoption of this technology has grown to more than 40 nations and regions.