A passage is an underground way, dug through the encompassing earth and encased with the exception of entry and exit. The first burrowing safeguard was created by Marc Isambard Brunel in January 1818 underneath the Thames Waterway in London. The Bangabandhu Passage Task under the Karnaphuli waterway is planned as a solitary layer 4-path double carriageway with two safeguard burrows.

Burrow Exhausting Machine(TBM):

The Passage Exhausting Machine (TB) utilized during the exhuming works for the Passage development under Karnaphuli Stream is air-pad slurry pressure adjusted safeguard machine, fabricated by Tianhe Mechanical Hardware Assembling Organization Restricted (CCCCTH). The measurement of the Cutterhead was 12.12m with a 13.6m long safeguard segment.

The assembling of the TBM utilized for the passage was started in Walk 2017 by readiness of drawing of cutterhead, safeguard skins, erector, trolly structure, portion dealing with framework and fragment feeder and funneling plan for the primary body. The full plan was concluded toward the finish of July 2017. The request for the assembling of this slurry safeguard TBM was put in April 2017 by CCCC during the plan phase of the Venture. The creation stage was 120 days from the center of May 2017 after the acquisition of plates for the principal body. It required 100 days something else for the gathering, appointing and production line acknowledgment test up to finish of December 2017


The primary parts of the TBM are the followings:

• Safeguard Body (front, center and tail safeguard)

• Cutters and Duplicate shaper

• Drive Framework

• Oil and Grease Arrangement of Principal Bearing

• Instigator

• Pneumatic force Control Arrangement of Air Chamber

• Drive Framework

• Section Erector

• Cooling Water Framework

• Squander Water Release Framework

• Slurry Transportation Framework

• Man-lock

• Pipeline augmentation Framework

• Coordinated Grouting Framework

• Portion Capacity and Transportation

• Auxiliary Grouting Framework

• Air Packing Framework

• Modern Controlled Blower Framework

• Crisis Producing Set

• Fundamental Ventilation Framework

• Assistant Ventilation Framework

• Direction Framework

Safeguard Machine Get together Plan:

Each safeguard is partitioned with four sections Upper Block, Left and Right Block and Lower Block. For Safeguard Machine Lifting, 500t Super Crawler Crane are utilized for Raising and gathering in the functioning admirably.

The grouping of establishment of Safeguard Machine are as per the following.

1.First of all, the Lower section of the steel sleeve is raised set up;

2.Front (F2) and Center Safeguard (B3) Lower part is raised down to the shaft;

3.Drive part is raised down to the shaft and collecting;

4.Front Safeguard Left (F3) and Right (F4) and Upper (F1) Block are raised down to the shaft;

Shaper Head:

The Shaper head is collected on the Ground. Two Crawler cranes are utilized to transform over the cutterhead and lower into the functioning shaft. The in general lifting weight of the cutterhead is 220T.

There are two kinds of Shaper Head for Delicate Ground Safeguard Machine.

• Spoke Type;

• Plate Type;

The cutting wheel is furnished with various types of Cutting Instruments:

• Scrubbers/Primary Shaper 282 ;

• Going before/Essential Shaper 159;

• Shell Shaper 25;

• Wear Identifier 2;

• Twofold Edge Hard core Tearing Shaper 12

• Fringe Insurance Shaper 25;

• Fish Tail Shaper 1;

TBM Supporting Streetcar Get together Plan:

After Safeguard collecting, the match streetcar is gathered to the on location get together of 1# , 2#, 3# and 4# as per the saved lifting opening (Length 20mXWidth 7.5m) at C&C segment.

Shaper Head:700mm

Streetcar 1: 14.35m

Streetcar 2: 17.65m

Streetcar 3: 14.50m

Streetcar 4: 16.80m

Going before Works of TBM Send off: Vertical Freezing Support:

Vertical Freezing Support is an approach to built up soil which can help before the TBM send off. The functioning shaft end is merged through Ø1200@800 triple-tube HP compound beating heaps. To keep away from shaper plate wear when the safeguard begins, vertical Freezing Support is used.The thickness of the freezing wall is 1.5 m, the width is 16.0 m, and the freezing profundity is 25 m. The principal column of openings is 400 mm from the side line of the substantial score wall, the distance between the openings is 800 mm, including 21 ones. The subsequent column is 800 mm separated from the primary line, lurched with the main line in plum bloom shape in 20 openings.

On the posterior of the Shaper Top of this Safeguard Machine, a Safeguard Parcel is introduced. The Space between the Parcel and the Shaper Head is named "SLURRY Lodge". The slurry made of water, mud and added substances is squeezed into the Slurry Lodge through the Pipeline and the slurry fills the whole Slurry Lodge with a specific strain to shape a slurry pressure chamber. At the point when the Safeguard Machine propels, the earth and sand cut by the cutters is blended by the mixing gadget to frame high-thickness slurry which is shipped off the Slurry Treatment Plant on the ground through liquid transportation and the dirt and water are isolated and afterward back to the Slurry Lodge.

Going before Works of TBM Send off: Establishment and Troubleshooting of Slurry Station:

Before Safeguard Burrowing begins, new Slurry ought to be ready and put away in the slurry tank. Unrefined components of slurry are bentonite and water, and the extent of bentonite and water (blend proportion) is 1/0.135.The natural substances are blended in with high velocity turning blender in the wake of being placed into the planning barrel. In the wake of blending, the slurry is put away in a slurry stockpiling pool for reserve and will be siphoned into the slurry flowing pool after 24h for use. The multi path Street Passage under the Stream Karnaphuli fundamentally goes through the firm soil and sand layer interbedded from shallow to profound and the entire area, fine sand layer is exhumed. Add 45t Bentonite to every one of the 10 rings subsequent to burrowing. While blending, add the mud slurry which is put away in the past period to diminish how much bentonite.

Going before Works TBM send off: Establishment of Steel Sleeve:

Before TBM Send off, the Safeguard Machine is fixed with the Steel sleeve. The Steel Sleeve is a 20mm thick Steel Plate on which is given a rib plate to keep up with its firmness. A tension equilibrium is implicit development inside the sleeve and afterward the TBM goes through the entryway to complete the process of sending off. The Counterforce section gives a counter-power to TBM during TBM send off. Sand is filled in the sleeve to give power of contact and oppose against winding. An Enemy of force Rib is welded on the TBM to oppose against force.