Progress Report > Package IA - North Tunnel Section

Physical Progress | Photographs | Construction Supervision

Physical Progress

Contractor	JV of Hazama and Cienco 6
Commencement of the Works	1st October 2000
Time Elapsed (days)	876 of 1460 (60%) Remaining 584days
Progress
Main Tunnel(3857m)	65.90m in this month; 2,165.5m in total (56.14%)
Evacuation Tunnel(3857m)	35.70m in this month; 2,119.8m in total (54.96%)
Ventilation Tunnel(1810m)	33.30m in this month; 1,856.31m in total (97.88%)
Others

 

Photographs

	North Portal Area
	Ventilation Adit Portal Area
	Explosive Charging at Main Tunnel
	Shotcrete Spraying at Main Tunnel
	Preparation for Foundation Beam Construction
	Waterproofing Works
	Setting of Form for Concrete Lining
	Initial Pouring of Concrete on Niche Form
	Joint Site Inspection of Overbreak
	Mucking After Blasting at Main Tunnel Sta. 3+786.8 (Dis. Fr.Portal: 2,143.80m)
	Main Tunnel After Blasting at Sta. 3+769 Bad Geotechnical Condition - Fracture Zone (under support type III)
	Foundation Beam Poured Concrete / Leveling Poured Concrete at Main Tunnel Sta 3+407.5
	Excavation for Foundation Beam at Main Tunnel Sta 3+ 450 (Infront of Backfilled Temporary Cross Passage)
	Completed Lining Concrete at Layby No.3 and Vehicular CP Connection Sta 2+800
	Setting Form at Main Tunnel Layby No.4 with Cross Passage No.4 Sta 3+190
	Tunnel Face Drilling at Evacuation Tunnel
	Shotcrete Spraying at Evacuation Tunnel
	Drilling for Blasting at Evacuation Tunnel Beside Temporary Niche No.11 Sta 3+754.6 Sta 3+754.6 under Supporting Type II
	Evacuation Tunnel at Same Station - Poor Rock Condition Crushing Zone (Class C1)
	Mucking at Ventilation Adit
	Face Drilling at Electrostatic Precipitator
	Shotcrete Sprauing at Electrostatic Precipitator
	Chipping Works at Electrostatic Precipitator No.1 Sta 0+086.2 (Exca. L=71.8m) in Good Rock Condition - Class B to A
	Chipping Works at Electrostatic Precipitator No.1 Sta 0+086.2 (Exca. L=71.8m) in Good Rock Condition - Class B to A
	Site Visit of Vice Prime Minister Nguyen Tan Dung
	Site Visit of jibic Representative - Mr. Takayuki Sato
	Safety Assembly

Construction Supervision

Summary

As of February 25, 2003, total Length of Main Tunnel Excavation reached to Sta. 3+793.8 or 2,140.8 meters (including Six (6) Laybys) from the Tunnel Portal.

Forty-Two (42) Niches (10 Emergency & Call Niche and 32 Firefighting Niches) were completely excavated inside the Main Tunnel.

Concreting of the Foundation Beam and Concrete Lining Works at the Main Tunnel were carried out. As of February 25, 2003, Concrete Lining construction has reached to 1,618.5 meters.

As of February 25, 2003, total length of Evacuation Tunnel excavation reached to Sta. 3+754.7 or 2,101.7 meters from the Tunnel Portal.

Five (5) Cross Passageways were completely excavated across the Evacuation and Main Tunnels. 

As of February 25, 2003, total length of Ventilation Adit Excavation reached to Sta. 0-103.5 or 1,853.0 meters from the Tunnel Portal.

Exhaust Tunnel excavation at the Ventilation Adit was started and as of February 25, 2003, total length of excavation reached to 2.9 meters long.

As of February 25, 2003 total length of the 1^st Electrostatic Precipitator excavation from ending connection of the Main Tunnel reached to Sta. 0+083.5 or 60.7 meters and 9.6 meters or Sta. 0+017.2 from beginning connection of the Main Tunnel.  Total length of excavation reached to 70.3 meters

Main Tunnel 

• Excavation

For the month of February 2003, the geological condition was very poor and over- breaks occurred on almost every cutting face. Over the whole month, supporting type III and type II, with some pattern rock bolts and 10-cm thick shotcrete were instructed by the Engineer. Therefore, the progress was affected by the geological condition and also by the excavation of some rounds of the Electrostatic Precipitator done by the Main Tunnel Group. Overall, the rock condition encountered this month was classified as Class C1. This month, the excavation of Main Tunnel was shorter due to the excavation of EP and due to the poor maintenance of equipment that causes frequent breakdowns on almost every shift. The excavation was extended by 65.90m (station 3+742.6~ 3+808.5). This gives a total length of 2,165.50m (Progress: 56.14%) from the tunnel portal.

• Electrostatic Precipitator No.1 (Excavation)

This month, the excavation of the Electrostatic Precipitator No. 1 has been going on from the outlet side based on the newly approved location on station 3+643.04 along the centerline of MT. The Main Tunnel group carried out the excavation of the EP simultaneous with the Main Tunnel until 14^th of February 2003. The Evacuation Tunnel group replaced the Main Tunnel group and continued the excavation of EP after completing the excavation of the Pedestrian Cross Passage No.4 (Cross Passage No.5). Four rounds on the Inlet side were also excavated this month. The geological condition encountered was in good condition and was classified as class B to A.

The EP Tunnel has a design length total 137.6m from sidewall to sidewall of the Main Tunnel. A length of 68.4m was excavated on the Outlet side and a length of 10.1m was completed on the Inlet side, totaling a length of 78.5m. Remaining length to be excavated is 59.10m.

• Niche Excavation:

Forty-two (42) Niches – Ten (10) Emergency Call Niches and Thirty two (32) Firefighting Niches – in the Main Tunnel were already excavated. Excavation of niches continues according to the designed niche distribution plan.

• Lay-by Left No.1, 2, 3 and Right No.1, 2, 3

The Lay-by Left Nos. 1, 2, 3 and Lay-by Right Nos. 1, 2, 3 in the Main Tunnel, which has a total length of thirty-two (32) meters each, were completed as per original plan.

• Behind Works (Behind Tunnel Excavation)

The pouring of Class D concrete for the Foundation Beam of the Lining Concrete continued this month from Station 3+323.5 to 3+457.5 with a total length of 134m on each side.

Installation of Mole Drain Pipes, together with filter cement aggregate, on both sides of the tunnel continued simultaneous with the foundation beams.

Cutting of Rock bolt heads and installation of geo-textile covers were done on areas with random/safety rock bolts.

Installation of EVA Waterproofing Membrane also continued following the covering of random rock bolts. The completed laying/installation of membrane reached to station 3+379.0, totaling a length of 1,715m. The Engineer continued to require testing of the welded joint sheets using air pressure test, as per procedure stated on the method statement, before continuation of the installation.

Pouring of Concrete Lining was also carried out as per approved design segment. The Engineer carefully checked, during the joint survey with the contractor, the setting of the form for both bulkhead sides and the thickness as per design requirements.

The Concrete Lining for Standard Section of the Main Tunnel completed until the end of this month totaled to 1,535.10 meters. The Concrete Lining works for Lay-by Left Nos. 1, 2 and Lay-by Right No.1 in Main Tunnel, totaling a length of 93m.

The Main Tunnel Concrete Lining completed up to this month totaled to 1,628.10m (Progress: 42.21%).

For the Pedestrian Cross Passage No. 1 (station 2+000), No. 2 (station 2+400) and Vehicular Cross Passage No.1 (station 2+800), concrete lining works for the blocks connected to the Main Tunnel Lay-by Section, which has a total length of 10.5m, were completed.  Setting of steel frames for concrete lining forms of Pedestrian Cross Passage No. 3 has been started..

Evacuation Tunnel

In the beginning of February 2003, the encountered geological condition consisted of fracture zones and slickensides, which were under supporting type II. Although four rounds were under supporting type I, the rock condition still has some joints. In addition, after those rounds, crushing zone appearing from right hand side towards the crown part so the RE gave instruction again to change the supporting system to type II and, later on, to type III until the end of this month. The excavation for the Evacuation Tunnel was temporarily stopped on 9^th to 14^th of this month to execute the Pedestrian Cross Passage No.4 (CPNo.5). In addition, the excavation of the Electrostatic Precipitator had also been executed by the ET group simultaneous with the excavation of the Evacuation tunnel.

Generally, the rock was classified as class CI to B.

The excavated length this month was only 35.70m (station 3+727.1 ~ 3+762.8), giving a total length of 2,119.80m  (Progress: 54.96%) from the tunnel portal.

The Temporary Transformer Niches No. 1~11 were completely excavated as per approved plan submitted by the Contractor.

The Enlarged Pedestrian Cross Passageway Nos. 1, 2,3 and 4 and Vehicular Cross Passageway No. 1 were completed.

The closing of the Temporary Cross Passage on station 3+450 was completed by backfilling it with blasted rock and by sandbag laying on the top crown part. The sidewall facing the Main Tunnel was sprayed with shotcrete on top of one layer wiremesh.

Ventilation Adit Tunnel

In the month of February 2003, the rock condition encountered was in good condition. Geologically, the rock condition was stable on class B. On some portions, it was almost classified as class A.

The excavation of the Enlarged Section was going on with the supporting system approved by the Engineer for the inner part and connection to Main Tunnel of Exhaust Shaft Section and Supply Clean Air section. The excavation of the Exhaust Shaft Section has also been started. The condition of the rock encountered was good.

This month in Ventilation Adit, the progress was very poor due to the problem of the Contractor on the ventilation system. The Contractor tried to modify the previous system of blowing fresh air from tunnel portal by reversing it suction system. However, the modification made was not successful. So, the Contractor borrowed one (1) unit of 200kw ventilation fan from PKIB Contractor and it was installed on February 26, 2003.  However, the installed ventilation fan has not started operating yet.  Furthermore, once its operation starts, improvement on the ventilation system in the Ventilation Adit will be under observation.     

The excavated length for the month of February 2003 was 33.30m (station 0+070.5 ~ 0-103.8), totaling to 1,856.31m (Progress: 97.88%) from the tunnel portal. The progress percentage includes the 144m-tunnel length extension for modification of ventilation system approved by the Employer.