Civil Blasting

A key pillar of Singapore’s impressive growth record was its infrastructure. Upgrading of public housing, road and rail network, underground utilities network and port facilities are regular features in Singapore’s infrastructure development. Often then not, new developments and projects are sprouting up in the build-up areas and populated neighbourhoods which requires careful planning when it comes to blasting works. During civil engineering works, such as blasting and excavation, noise and vibrations are generated which can affect residents and industrial activities in the vicinity. With the right mind-set, risk management, latest blasting product / systems and backed with the right personnel and experience, the works can be well executed with the minimal inconvenience or disruption to the neighbouring industry.

Shaft and Tunnel Blasting

While TBMs are used in many civil tunnelling projects, the initial underground excavation for the shafts and tunnels in rock is undertaken using blasting techniques for the launching of the TBMs. These underground works require special blasting techniques and systems to effectively excavate the rock. Major projects in Singapore such as the Jurong Rock Cavern, the underground MRT lines, the Deep Tunnel Sewerage System and the Cable Tunnels require the removal of big volumes of rock during construction.

Quarry – Open Blasting

Quarry blasting for aggregates or road way construction leading into the quarry for efficient land use and space management are other reasons for blasting to effectively break large volumes of the rock in our land scarcity island. Though such blasting technique are rare these days, other similar approach of blasting large rock volumes in a single blast are undertaken for new housing and MRT projects. Such large scale blasting is perhaps one of the most challenging aspects facing the industry as population and urbanisation has brought it closer to the operating sites where large volumes of rock are encountered.

Under Water Blasting

In some cases where dredging is met with extremely hard rock formation, underwater drilling and blasting operations are performed usually for harbour deepening, pipeline construction and extension of ports. With relevant experience in this field of work, we can provide the expertise to undertake the blasting works with our latest explosives products and systems.

Other Blasting Activities

Apart from construction blasting works, explosives are also used for geological / site characterisation projects normally termed as “seismic survey” works using explosives as a medium for the exploration of the earth’s sub-surface from the reflected seismic waves generated from the blast. Usually small charges are used for such projects and initiated individually over large span area or termed the survey lines. Other similar test are also carried out for liquefaction and calibration test based on the clients request.

Rock Bolting / Soil Nailing

Rock Bolting is used for securing the rock mass from collapsing or for improving the rock stability of the excavated face. It is an additional support form and it is usually followed by shotcreting. Soil nailing has the same philosophy but is used to maintain slope stability. Both are followed by shotcreting works and have a variety of bolts and nails depending on the geology. Applications can be found at road construction, tunnel construction, deep excavations, shafts, slopes, etc. Asia Tunnelling & Construction P/L have the adequate machinery, experienced personnel and staff to successfully manage these works at the top quality.

Wet / Dry Shotcreting

Shotcrete spraying has a variety of applications and plays a major role in temporary support. Wet or dry method is used together with wiremesh or steel fibers to form the temporary support for geotechnical works and is commonly used in tunnel construction. Depending on the nature of works, different equipment, technics and setting up is required for the smooth and successful completion of the project. Asia Tunnelling & Construction P/L have the adequate machinery, experienced nozzlemen and staff to successfully manage shotcreting works at the top quality.

Ring Beam Erection

Before constructing a Cross Passage or a Pump Sump, a steel bracing has to be installed to support the bored tunnel at the location where the segment will be removed. A ring beam has the diameter of the bored tunnel but can vary in thickness and span. Usually rings beams consist of five rings that are erected at the same time and jointed together by cross beams. An opening is available at the CP or PS location for removing the segment and accessing in to the proposed structure. Erecting a ring beam requires experienced personnel as working at height and lifting of heavy beams in a confined space can cause accidents.

Tunnel Eye Construction

Once the formation level is reached in a station box, the location where the TBM will start the journey will be marked. However, the ERSS structure is still in the way and has to be demolished to facilitate the launch. A tunnel eye is a demolition job that usually requires to demolish a 1.2m thick heavily reinforced wall and assess the ground conditions behind it before the TBM launch or retrieval. Demolition works can be done mechanical or even manually depending on site conditions.

TBM Thrust Beam Construction

Erecting the structure for TBM launching.

Ground Improvement / Grouting

Grouting is the procedure when a cement mix is pumped into a ground to improve its geotechnical characteristics and minimize the water ingress.Grouting is also used to fill up voids, gaps or pockets. Ground improvement is common in tunneling works before starting the excavation and to minimize the water ingress. Different types of grout mixes are available, depending on the geology faced at each project.

First Stage or First Bed Concrete in Bored Tunnel

First stage or First bed concrete is a concrete layer which is placed between the precast segment lining and the track concrete lining cast by the track work contractor.

After completion of TBM mining, there are numerous preparations prior to this casting. They are, removing the TBM supply line, dismantling the temporary tracks, cleaning the slurry from the inverts, grinding the segments, cleaning and protecting the segment grooves and so on.

This casting work is considered as a massive concreting operation in Tunneling works.

SWC Bracket Installation

After the first stage casting, the precast segment lining is drilled at dimple locations to install various brackets that will be used for cabling of live tunnel operation.

The brackets are fixed at the segment face by means of bolt and expansion anchors hammered into the drilled holes.

Cast in-situ reinforced concrete lining of cross passages & Pump sump

Cross passages are constructed to connect the twin tunnels, which will act as an emergency escape route; whereas the pump sumps are constructed in lower elevation of bored tunnels or of the cross passages to receive the water and will be pumped out throughout the lifespan of the bored tunnels.

The design opening is achieved by using aluminium or conventional formwork systems.