Construction Supervision

Summary

As of July 31, 2003, 154.8m were excavated in the Main Tunnel this month, giving a total length of 2,919.8m (progress 75.70) from the Tunnel Portal.

Fifty seven (57) niches (14 emergency & call niches and 43 Firefighting Niches) were completely excavated inside the Main Tunnel.

The Main Tunnel Concrete Lining completed up to the end of this month totaled to 2,214.4m (progress 57.14%)

As of July 31, 2003, 182.05m were excavated in the Evacuation Tunnel this month, giving the total length of Evacuation Tunnel excavation reached to 2,816.35m, (progress 73.02%) from the Tunnel Portal.

Main Tunnel 

• Excavation

In the month of July 2003, the rock encountered in the Main Tunnel was continuing in good condition. Geologically, the condition was stable on Class B. On some portion, it was classified as class A this month.

Total lengths of 154.80m were excavated in the Main Tunnel this month, giving a total length of 2,919.80m station 4+562.8 (Progress: 75.70%) from the tunnel portal.

• Niche Excavation:

Fifty-four (57) Niches – Fourteen (14) Emergency Call Niches and Fourty-three (43) 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, 4 and Right No.1, 2, 3(connected to EP Outlet), 4

The excavation of Lay-by Left Nos. 1, 2, 3 and Lay-by Right Nos. 1, 2, 3,4 in the Main Tunnel, which has a total length of thirty-two (32) meters each, were completed during the previous months as per original plan. Excavation of Lay-by Right No. 5 was completed this month.

• Main Tunnel Rear Works (Concrete Works)

The pouring of Class D concrete for the Foundation Beam of the Lining Concrete continued this month from Station 3+871.5 to 4+063.5 with a total length of 192m 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 rock bolts.

Installation of EVA Waterproofing Membrane was also continued following the covering of rock bolts. Until the end of this month, a total length of 2,342.00m (Station 1+664~4+006.00) was completely covered with waterproofing membrane. 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 2,059.40 meters. The Concrete Lining works for Lay-by Left Nos. 1, 2 and Lay-by Right No. 1, 2 in Main Tunnel, totaling a length of 155m. The Layby Left No.3 (Layby No.6) was also completed this month.

The Main Tunnel Concrete Lining completed up to the end of this month totaled to 2,214.40m (Progress: 57.14%).

For cross passages, only the concrete lining for the blocks connected to the Main Tunnel are being executed. Concrete lining completed until the end of this month includes the Pedestrian Cross Passage No. 1 (Station 2+000), No. 2 (Station 2+400) and Vehicular Cross Passage No. 1 (Station 2+800), and Pedestrian Cross Passage No. 3 (Station 3+190), No.4 (Station 3+688), totaling a length of 16.90m.

Cable Duct Bank Concreting:

This month of July 2003, the pouring of concrete for the cable duct bank with manholes, including two (2) lines of embedded conduit pipe with a diameter of 110mm each, were continuing from Station 1+699.0 and reached to Station 3+221.0, totaling a length of 1,453.69m.

Side Drainage/Catch Basin:

This month, the pouring of side drain and setting of pre-cast catch basins was on-going from station 1+670.45 and reached to station 2+482.95m for side drain, totaling a length of 770.9m. The setting/installation of pre-cast catch basins started from no. 2 ~ 39, totaling 38nos. (to station 2+595).

• West Side: (Right Side)

Side Drainage:

The conduit duct bank concreting under the walkway structure has been commence from station 1+691.55 and reached to station 2+341.33 giving a length 671.78m. 

Side Drainage/Catch Basin:

Casting on-site of side drainage on the west side of the Main Tunnel began at Station 1+670.45 and reached to Station 2+494.55 with a total length of 771.96m. The setting/installation of pre-cast catch basins were from no. 2 ~ 37, totaling 36nos. (to station 2+545).

Walkway Structure:

This month, the pouring of walkway structure commenced. The base concreting works was on-going from station 1+669.70 and reached to station 1+918.5m, totaling a length of 248.8m. The sidewall casting concrete were also starting on the same station and reaching to station 1+818.40 with a total length 126m. The casting concrete of hydrant pipe saddle inside the walkway structure were also simultaneously execute with a base concrete starting same station and reaching to station 1+841.50 a totaling 145.8m. 

 

• EP No. 1 Concreting Works:

The pouring of Class D concrete for the Foundation Beam of the Lining Concrete this month was completed from Inlet to Outlet connection to MT.

Installation of Mole Drain Pipes, together with filter cement aggregate, on both sides of the tunnel were also completed connection on the MT.

Installation of EVA Waterproofing Membrane both connections to the MT was completed this month.

The casting of Lining Concrete from block no. 1 Inlet (station 0+007.26) connected to MT and continuing up to block no. 16 (station 0+089.83) with a total length of 82.57m this month.

Evacuation Tunnel

For the Evacuation Tunnel was also in good rock condition up to the end this month. Geologically, the rock condition encountered for both faces (face nos.1 and 2) this month was stable on Class B. On some portion, it was classified as class A this month.

This month, the excavation face no.1 were connected through to the face no.2. The contractor excavated the PCP No.5, in order to excavate another cutting face (face no. 3) for ET and to shortening with its delay from the MT. The Contractor excavated the PCP No. 5 at Station 4+490 simultaneous with the excavation of Evacuation Tunnel Face No.2 by the same ET group. The excavation for Face No. 3 is on-going executing this month.

The Face No.1 to No.2 excavation length extended by 167.10m and excavation for Face No. 3 side yielded a length of 14.95m. Total excavation length for this month was 182.05m. The distance from the tunnel portal gives a total length of 2,816.35m (Progress: 73.02%). 

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 to 4 and the Vehicular Cross Passageway No. 1, 2 was completed. This Month, the Pedestrian Cross Passage No.5 were also completed and where using access to ET face No.3

Ventilation Adit Tunnel

• Concreting Works:

Cut and Cover Section / Connection Lining Concrete at Portal:

The Concrete Lining for Cut and Cover Section, with Portal Wall, and two (2) blocks of Normal Section of Lining Concrete connected to the Cut and Cover Section were completed with a total length 13.97m from Station 1+738.54 to 1+752.51.

Normal Section Lining Concrete:

Pouring of Class D concrete for the Foundation Beam of the Normal Section of Lining Concrete were continuing with a total length of 233.28m on both sides from Station 0-055.05 to 0+0161.22.  Block Nos. 17 ~40 were completed.

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 rock bolts.

Installation of EVA Waterproofing Membrane was started this month from station 0-056.0 ~ 0+088.5 with a total length of 161.5m. 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 has also commenced after the reassembly of the sliding form was completed and has been 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 Normal Section of the Ventilation Adit completed until the end of this month totaled to 54meters block no.17 to 22 (0-055.05 ~ 0-001.05).

The Ventilation Adit Concrete Lining completed, including Cut and Cover Section together with its connection to the normal section, up to the end of this month totaled to 67.97m (Progress: 3.60%).

The contractor was also excavated and setting concrete pipe diameter 400mm for Culvert No.3 at station 0+342.5 between Portal Plaza and access road as per approved plan by the Engineer.

Major Events and Issue

Site Inspections

On July 19, 2003, Mr. Vu Khoan – Vice Minister of the Government and his delegation inspected the Project.

Monthly Meeting

On July 09, 2003, a Monthly meeting was held at the Employers/Engineer’s Office between the Employer, the Engineer and the Contractor.

Safety Patrol and Meeting

On July 04, 2003, the Employer, the Engineer and the Contractors conducted a Safety Patrol on Package 1A and Package 1B Projects.

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