Construction Supervision

Summary

As of August 31, 2003, 157.40m were excavated in the Main Tunnel this month, giving a total length of 3,077.30m (progress 79.78%) from the Tunnel Portal.

Sixty (60) niches (14 emergency & call niches and 46 Firefighting Niches) were completely excavated inside the Main Tunnel.

The Main Tunnel Concrete Lining completed up to the end of this month totaled to 2,365.40m (progress 63.33%)

As of August 31, 2003, 174.35m were excavated in the Evacuation Tunnel this month, giving the total length of Evacuation Tunnel excavation reached to 2,990.80m, (progress 77.54%) from the Tunnel Portal.

Main Tunnel 

• Excavation

In the month of August 2003, although they have some safety rockbolts for slickenside and key block were instructed on site by the Engineer, 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 157.40m were excavated in the Main Tunnel this month, giving a total length of 3,077.30m station 4+720.5 (Progress: 79.78%) from the tunnel portal

• Niche Excavation:

Sixty (60) Niches – Fourteen (14) Emergency Call Niches and Fourty-six (46) 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, 5 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.

• 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 4+063.5 to 4+187.5 with a total length of 124m 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 2,445.0m (Station 1+664~4+109.0) was completely covered with waterproofing membrane. The Engineer still 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 2,191.40 meters. The Concrete Lining works for Lay-by Left Nos. 1, 2, 3 and Lay-by Right No. 1, 2, in Main Tunnel, totaling a length of 174m. The Layby Right No.3 (Layby No.5-1and 5-3) two (2) blocks was also completed this month and remaining one (1) block connection to EP No. Outlet was on-going preparation.

The Main Tunnel Concrete Lining completed up to the end of this month totaled to 2,365.40m (Progress: 63.33%).

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 August 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+525.0, totaling a length of 1,700.19m.

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 3+057.95m for side drain, totaling a length of 1,302.0m. The setting/installation of pre-cast catch basins started from no. 2 ~ 60, totaling 60nos. (to station 3+495).

• 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+808.12 giving a length 1,116.57m.

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 3+019.55 with a total length of 1,277.46m. The setting/installation of pre-cast catch basins were from no. 2 ~ 59, totaling 58nos. (to station 3+095).

Walkway Structure:

This month, the pouring of walkway structure was continuing. The base concreting works was on-going from station 1+669.70 and reached to station 2+408.5m, totaling a length of 738.8m. The sidewall casting concrete were also starting on the same station and reaching to station 2+164.60 with a total length 494.9m. 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 2+408.07 a totaling 738.37m.

• EP No. 1 Concreting Works:

The pouring of Class D concrete for the Foundation Beam of the Lining Concrete 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.

The casting of Lining Concrete from block no. 1 Inlet (station 0+007.26) connected to MT and continuing up to block no. 26 (station 0+140.61) with a total length of 133.35m (Progress: 97.12%) this month. The Block No.27 Outlet, which is connection to Layby No. 5-2 MT, was on-going preparation for concreting until the end of 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.2 and 3) this month was stable on Class B. On some portion, it was classified as class A this month.

This month, the excavation face no.2 were connected through to the face no.3. The contractor excavated through the PCP No.5 from last month, that where using to excavate the cutting face no. 3 for ET and in-order to shortening with its delay from the MT. The Contractor excavated the Face No. 2 simultaneous with the excavation of Face No.3 by the same ET group. The excavation for Face No. 3 is on-going executing this month.

The Face No.2 excavation length extended by 34.50m and excavation for Face No. 3 side yielded a length of 139.95m. Total excavation length for this month was 174.35m. The distance from the tunnel portal gives a total length of 2,990.80m (Progress: 77.54%). 

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 5 and the Vehicular Cross Passageway No. 1, 2 was completed.

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 including for Enlargement Section of Lining Concrete were continuing with a total length of 752.69m (station 0-120.05~0+615.09) on left side and the right sides a length total 704.78m (station 0-108.59~0+591.05).

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 for Normal Section was continuing this month from station 0-056.0 ~ 0+495.5 with a total length of 568.5m. The Enlargement Section was also starting installation at Adjustment Section end face walls. 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 Normal Section of the Ventilation Adit completed until the end of this month totaled to 364.17meters block no.17 to 56 (0-055.05 ~ 0+309.12).

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 378.14m (Progress: 20.03%).

As have been agreed among the Employer, the Engineer and the Contractor, chemical treatment water-stop injection shall be executed to reduce the water seepages in the Ventilation Adit. The materials that will be used for the chemical injection are Denka ES and Setter D-100 mixed with cement milk.

In the month of August, the manpower and equipment for the chemical injection in Ventilation Adit were mobilized. A joint inspection among the Employer, the Engineer and the Contractor was conduct on August 11,2003 for the confirmation of the areas where the chemical injection would be necessary to be executed for the reduction of water seepage.

After all the equipment was confirmed to be working well, the chemical injection works commenced. At this time, chemical materials were injected on area with major water seepages between station 0+790.0m to 0+770.0m. Pattern (primary) holes will be injected with chemical in September.

Until the end of August 2003, thirty-one (31) pattern holes were drilled and fifteen (15) holes were injected with chemical material.

Major Events and Issue

Site Inspections

On August 18, 2003, Prime Minister Phan Van Khai and Vice Minister Nguyen Viet Tien and their delegation visited the Project.

Monthly Meeting

On August 06, 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 August 07, 2003, the Employer, the Engineer and the Contractors conducted a Safety Patrol on Package 1A and Package 1B Projects.

NATM Training Course B:

NATM Training Course B was started on August 04, 2003 and lasted on August 29, 2003 at Cience 6 Site Office where professors from Japan and Hazama-Cienco 6 J.V’s Japanese Managers was the lecturers.

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