Construction Supervision

Summary from Contractor

As of October 31, 2003, 150.00m were excavated in the Main Tunnel this month, giving a total length of 3,376.3m from the North Tunnel Portal and South Side giving 480.7m, overall total length 3,857m for completed 100%.

Sixty three (63) niches (15 emergency call niches and 48 Firefighting Niches) were completely excavated inside the Main Tunnel. The Main Tunnel Concrete Lining completed up to the end of this month totaled to 2,670.50m (progress 69.24%)

As of October 31, 2003, 141.90m were excavated in the Evacuation Tunnel this month, giving the total length of Evacuation Tunnel excavation reached to 3,290.20m, (progress 85.3%) from the Tunnel Portal.

Construction Supervision by Engineer

Main Tunnel 

• Excavation

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

To achieve the tunnel breakthrough in October, which was strongly requested by the Consultant and the Employer, the contractor changed his method of excavation from full-face excavation to top-heading excavation starting at station 4+900.7 until station 5+013.5 where it breakthrough with the pilot tunnel excavated from the south side.

As per the schedule requested by the Employer, the final breakthrough was done on October 30, 2003 with a small ceremony prepared by the contractor and was attended by PMU85 and Consultant Managers on site.

Bench excavation has been continuing from station 4+900.7 and has reached station 4+962.0, with a length total 61.30m, until end of this month.

A total length of 150.00m until station 5+019.3 was excavated in the Main Tunnel this month, giving a total length of 3,376.30m from the North tunnel portal and South Side giving 480.7m, overall total length 3,857meters for completed 100%.

• Niche Excavation:

Sixty three (63) Niches - Fifteen (15) Emergency Call Niches and Fourty-eight (48) 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, 4, 5 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+406.5 to 4+577.5 with a total length of 171m 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 2,892.0m (Station +664~4+556.0) 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 2,453.50 meters. The Concrete Lining works for Lay-by Left Nos. 1, 2, 3, 4 and Lay-by Right Nos. 1, 2, 3 in Main Tunnel, totaling seven laybys with a length of 217.00m, were also completed.

The Main Tunnel Concrete Lining completed up to the end of this month totaled to 2,670.50m (Progress: 69.24%) .

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. 1~4 (Station 2+000, 2+400, 3+190, 3+688) and Vehicular Cross Passage No. 1~2 (Station 2+800, 4+100), totaling six (6) Cross Passage with a length of 20.10m.

Cable Duct Bank:

In the month of October 2003, the concrete works for the cable duct bank with manholes, including the installation of two (2) lines of embedded conduit pipe with a diameter of 110mm each, has been completed until Lay-by No. 6, the total length poured reaching to 2,152.00m (sta.1+669 ~ 3+821).

Side Drainage/Catch Basin:

This month, the pouring of side drain and setting of pre-cast catch basins was ongoing from station 1+670.45 and reached to station 3+644.55m for side drain, totaling a length of 1,966.10m. The setting/installation of pre-cast catch basins started from no. 2 ~ 83, totaling 82nos. (to station 3+695).

• West Side: (Right Side)

Cable Duct Bank:

The conduit duct bank concreting under the walkway structure has been commenced from station 1+691.55 and reached to station 3+493.12, giving a length 1,824.12m.

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+619.55 with a total length of 1,942.06m.

The setting/installation of pre-cast catch basins were from no. 2 ~ 83, totaling 82nos. (to station 3+695).

• 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 3+251.5m, totaling a length of 1,581.80m. The sidewall casting concrete were also starting on the same station and reaching to station 2+935.7 with a total length 1,266.0m. 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 3+115.5 a totaling 1,445.80m.

On October 29, 2003, a joint site inspection between the Consultant and contractors of Package IA, III and IV was held prior to handing over of the walkway structure by Package IA to Package III/IV. Although some minor items were needed to correct, part of the walkway structure, from station 1+670.00 to station 2+384.50 was, nevertheless, the hand over to E, M was agreed, and it is for their works access only.

• Main Drainage:

The Perforated Concrete Pipe diameter 400mm began at station 1+709.4 and reaching to station 2+605.5 with total length of 896.1meters including setting/connection of pre-cast concrete manhole f rom no.1~4 and connection of cross drain from pvc mole drain.

• EP No. 1 Concreting Works:

In the month of October 2003, all concreting works including Sewage Pit and Pavement were completed. The Electrostatic Precipitator No. 1 was turned over to PKIII/PKIV on the 10th of this month.

Evacuation Tunnel

The rock encountered in the Evacuation Tunnel was also in good condition, although, on some rounds, installation of safety rock bolts became necessary due to slickensides with white clay band. Geologically, the rock condition encountered was stable on Class B. On some portion, it was classified as class A.
This month, the contractor continued the excavation of Face No. 4 through TCP No. 4 and passed through the location of the Pedestrian Cross Passage No.6(CPNo. 8).

The Face No. 4 excavation length for this month was 141.90m. The distance from the tunnel portal gives a total length of 3,290.20m until station 4+971.30 (Progress: 85.30%).

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 have been completed.

Ventilation Adit Tunnel

• Concreting Works:

Cut and Cover Section / Connection Lining Concrete at Portal:

The Concrete Lining f or 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 as well as for Enlargement Section of Lining Concrete has been continuing and reached a total length of 846.54m (station 0-135.11~0+866.15) on left side and 886.72m (station 0-135.11~0+746.6) on the right side at the end of this month.

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 has been continuing this month f rom station 0-055.05 ~ 0+722.5 with a total length of 794.06m. The installation waterproofing membrane on the Enlargement Section to Clean Air Supply and Exhaust Sections was also completed.

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 622.32meters f rom block no.17 to 81 (0-055.05 ~ 0+567.27). Concrete lining f rom block 14 to 7 ( 0-065.05 ~ 0-108.59) of the Enlargement Section was also completed, giving a total length of 43.54meters.

The Ventilation Adit Concrete Lining completed, including Cut and Cover Section together with its connection to the normal section and enlargement section, up to the end of this month totaled to 679.83m (Progress: 36.02%) .

Main Drainage:

The Perf orated Concrete Pipe diameter 300mm was continuing section no.1 began at station 0-066.83 to station 0+304.0 and section no.2 f rom station 0+504 to 0+655.0 with total length of 521.83meters including setting/connection of pre-cast concrete manhole from no.1 at the bottom part of VA intersection of Exhaust Shaft Section.

Center Wall Concrete:

This month, the first lift casting of center wall together with the foundation were commencing f rom the station 0-055.05 and reaching station 0+161.22 with a length total 153.27meters..

Grouting Works:

In the month of October 2003, the chemical injection on areas with major water seepages as well as on the primary pattern holes on Sections D, C and A were completed. The chemical treatment injection using Denka ES mixed with Setter D-100 and cement milk were completed before the rainy season has started and it was observed that the water seepages on the mentioned locations were drastically reduced.

However, after the start of the rainy season with some heavy rain, the water seepages between Sections D to A were observed to have increased again. Hence, during the joint site inspection among the Employer, the Consultant and the contractor on October 1st, 2003, the Employer and the Consultant decided the necessity of secondary injection holes and instructed the contractor to proceed with the drilling of and injection of chemicals to secondary pattern holes. The contractor commenced with the drilling and injection of chemicals to secondary pattern holes on Section D until the end of this month.

Major Events and Issue

Monthly Meeting

On October 01, 2003, a Monthly meeting was held at the Employers/Engineer 's Office betw een the Employer , the Engineer and the Contractor.

Safety Patrol and Meeting

Safety Patrol to both Packages was conducted by the Employer, the Engineer, and the Contractors on the morning of October 02, 2003 and held meeting on safety related issues in the afternoon.

Safety Patrol and Meeting

Safety Patrol to both Packages was conducted by the Employer, the Engineer, and the Contractors on the morning of October 02, 2003 and held meeting on safety related issues in the afternoon.

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