Tunnel Form Technology

GEM has been appointed as a project manager by one of the reputed developers in India, at their project in Pune wherein tunnel formworktunnel formwork system is being used. This is our first experience with the Tunnel form technology. The project has a built-up area of 13.83 lakhs sq.ft. in (Phase 1) out of which about 10 lakhs sq.ft. built-up area will be made using tunnel form. RCC part of each of the 22 story buildings is planned to be completed in just 4 months with half set of formworks. The tunnel forms can thus be released and be available for Phase 2 of the same project!
Tunnel form technology like any other new technology requires attention to many aspects and challenges of construction in a different manner than in conventional works. Some of these challenges may be:

• The planning of the building should lend itself to the adoption of tunnel form technology. That is why the decision to use tunnel form should be taken even before the schematic of the building is finalized.
• Similarly, the tunnel form supplier should also be on board from an early stage so that their inputs to optimize cost of tunnel form can be incorporated in design if possible. In time delivery of tunnel forms can also be assured by having the vendor on board early.
• The number of flats (repetition) should be large enough to justify the higher capex on tunnel form.
• The concrete mix should be carefully designed to allow pouring all concrete in one pour and should have the right workability and early strength development.
• Other resources like tower crane, concrete batching and rebar handling and placement should match the speed afforded by tunnel form
• Trained manpower should be available to handle the tunnel form as it has more to do with assembly (mechanical work) than carpentry!
• The form work must be handled and maintained carefully else many of the advantages will evaporate.

At the same time, Tunnel form technology offers many advantages over conventional beam-column-slab construction which may overcome above mentioned challenges faced by designers, construction managers and contractors. Many of these advantages hold good even when it is compared with monolithic slab-wall type of construction using Aluform (popularly known as Mivan technology).
Major Advantages of Tunnel Form System:

• High seismic resistance due to monolithic slab & walls construction
• Monolithic structure reduces number of joints and improves water tightness
• Reduce labour costs (greater requirement of tower crane)
• Reduce mobilization costs on site
• Reduced construction times (2-3 days slab casting cycle can be achieved) which is up to 3 times faster than conventional
• Higher quality finishes &#;Fair faced finish concrete can be achieved
• No need for plastering

If the technology is adopted right from the planning and design stage, project costs savings up to 25% can be achieved.

Tunnel Form Construction Technique

What is Tunnel Form Construction Technique?

In Tunnel Form Construction Technique contractors can cast slabs and walls in short cycle. It helps in combining the quality, speed and accuracy of off-site/factory production with the economy and flexibility of in-situ construction and Tunnel Form is recognised as a modern method of construction (MMC).

With Tunnel Form technique we can create cellular reinforced structure and these type of structures have high quality surfaces that require only minimal finishing. In Tunnel Form technique the facades and walls can be easily completed with thermally insulated units that can be clad as required.

In short, the Tunnel Form technique creates an efficient load-bearing structure that can be used in a wide variety of applications. 

 

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In which type of projects Tunnel Form Construction Technique can be used?

Tunnel Form Construction Technique is widely used in the construction of cellular structures that involve high degree of repetition such as:

• Private Housings
• Hotels
• Hostels (Student Accommodation)
• Prisons
• Commercial Complex
• High Rise Buildings

What are the benefits of using the Tunnel Form Construction Technique?

• Smooth and fast operation &#; due to use of use of reinforcing mats/cages and prefabricated forms
• Enhances quality of construction &#; precision of the formwork creates a smooth and high quality finish
• Flexibility in design and layout &#; with the help of large bays constructed using tunnel form
• Ensures higher standards of safety &#; edge protection systems, integral working platforms, minimal requirement for tools & equipment and predictable & repetitive nature of the tasks ensures higher standards of safety
• Value for money &#; reduces transportation costs, near zero wastage, just-in-time deliveries, reduces labour requirement and fast construction leading to lesser cost of financing
• Environment friendly &#; no wooden materials are used and also minimises heating costs & air-conditioning requirements in comparison to conventional buildings

What are the limitations of the Tunnel Form Construction Technique?

• Tunnel Form is not suitable for small projects, and projects that involve huge variations in design
• Initial investment of formwork and other machineries
• In case of imported formwork finalisation of plan is required sa early as 5 to 6 months
• In tunnel form system, skilled labor force is required in comparison to the traditional systems
• Building design should be suitable for the system
• Speedy construction demands high cash flow
• In case of some geometrical forms and angles special formwork needs to be designed, this attracts additional cost to the project