Another scandal broke out in Hong Kong's public works projects. "Hong Kong 01" received news that this Tuesday (21st) during the drilling of the T2 trunk road and the Cha Kwo Ling Tunnel Project, a hole was suspected to have appeared on the seabed, causing the materials in the pipeline to be mixed with seawater. , about 20 meters away from Cha Kwo Ling seaside, jetting like a fountain, some citizens took a video and spread it wildly.
Sources pointed out that the cause of the accident is still under investigation. It is reported that the engineering consulting company tends to believe that the hole was not backfilled during the previous exploration. It is related to drilling through the seabed, describing this incident as very rare.
Ni Xueren, a senior civil engineer, pointed out that if the accident is the former, the situation is quite serious or cause serious delays in the project; if it is the latter, it can be large or small, and the hole will change the water pressure of the pipeline and directly endanger the health of the workers.
He also pointed out that in theory, there are engineers to supervise the work, and there are also documents to record whether the backfilling of the exploration holes has been completed. I believe that someone should be held accountable according to the contract.
The contractor of the T2 Trunk Road and the Cha Kwo Ling Tunnel Project is Bouygues Travaux Publics. "Hong Kong 01" has inquired from the Civil Engineering and Development Department, Bouygues and its parent company Hong Kong Baojia.
The reporter went to the area where the incident happened this morning. Workers were working as usual, and people came in and out of the site from time to time.
As for the surface of the sea where the "fountain" once appeared, there is no abnormality, and it is believed that the sediment of that day has dispersed.
According to sources, the incident occurred at about 1:00 p.m. on Tuesday. The contractor was drilling the T2 Trunk Road and the Cha Kwo Ling Tunnel in the water area outside Cha Kwo Ling Road with a tunnel boring machine (TBM). The seabed is perforated, causing airflow to enter, and the thickness of the soil on the seabed cannot bear the relevant pressure, causing
bentonite slurry to spurt out, forming a phenomenon like a spring.
The source said that after the incident, the tunnel drilling project did not stop, "the hole will not be filled, the hole will be covered by the mud itself", but because the TBM's drilling project has passed the hole involved
, "Under the hole, it has become a tunnel", so there is no "fountain" phenomenon, and the relevant mud has also settled, so the sea looks clear.
According to sources, the engineering consulting company is investigating the incident, and
it is initially believed that the geotechnical team did not properly backfill the relevant hole after drilling holes under the seabed for land exploration
. There is a hole here, so when a TBM walks through, the air can go through this hole, so 'bulu' sprays things out."
It is reported that the incident may involve poor supervision of the consulting engineering company.
"I didn't check whether the contractor (contractor) had poured the slurry back, so I let him go." The
contractor may also have improper engineering.
It is understood that the consultant The company is going through the documents of the day to check whether there is grouting and filling of the hole after the land exploration is completed. "Whether you have filled in the seabed or not, I don't know. You have not verified (confirmed), unless there are some records (records) you Take a look at the powder and fill it up.”
As for whether the tunnel will cause safety problems, the source said that the tunnel may lose the protection of the soil and come into direct contact with seawater. A lot of water seeped into the tunnel, and water seepage may occur", and I was even more worried that "there will be a chance to explode more turns next time."
The source also mentioned that even if the project continues, there are more uncertainties at the bottom of the sea, and the risk of workers diving into the bottom of the project increases, or it may be difficult to repair the TBM or replace the "cutter head" for it. "If something happens suddenly , suddenly there is an accident, stop, or break down, and he can’t send people out to repair it at all.” It is estimated that the project may be severely delayed.
Senior civil engineer Ni Xueren.
(File photo/Photo by Lin Ruoqin)
Ni Xueren, a senior civil engineer, explained that if the seabed is drilled through, the situation is quite serious. "A tunnel is pierced through, so some materials are inserted into it. Because of the pressure, it is like a fountain spewing out." He continued,
Ruohai The bed was drilled through, and it is believed that it touched the broken zone, "it was so easy to fall all the way after changing her."
He said that this situation may involve insufficient survey work.
"Is it the lack of geological survey? It must be, because it can't find such weak places, but sometimes even if you do a lot, it may not be what you want. He continued to point out that the project will be delayed and it will take some time to rectify it.
If the accident only involved the exploration of the seabed without backfilling, Ni Xueren said that it would depend on whether seawater or debris flowed into the pipeline, which may affect the drilling machine. However, since the hole is relatively small, the problem can be roughly solved by backfilling properly.
However, he emphasized that related accidents can be large or small, because the pressure of the pipeline is different from that of the ground, and the hole will suddenly change the water pressure of the pipeline, directly endangering the health of the workers, and may suffer from "diver's disease" and various pain symptoms.
Ni Xueren also mentioned that
during geological exploration, the soil will be sampled for testing, and then the engineer in charge of the supervision will decide whether to continue the exploration drilling or backfill.
He continued to point out that there are documents that clearly record whether the backfilling has been completed.
In addition to the exploration contractor, the supervisor may also be responsible. The final responsibility depends on the content of the contract.
The T2 trunk road and the Cha Kwo Ling Tunnel are a two-lane two-way trunk road about 3.4 kilometers long, connecting Kai Tak and Lam Tin, of which about 3.1 kilometers are tunnels, which are expected to be completed in 2026.
The project contractor is Bouygues Civil Engineering, and the consultant company is Ancheng-Maijin joint venture. The total contract price is 10.918 billion yuan.
According to the information of the Land and Development Department, since the project involves the construction of the main road under the seabed of the Kwun Tong Typhoon Shelter, a drilling and excavating machine is required. The front of the machine is equipped with a rotary cutter head and can be drilled at a depth of more than 40 meters below sea level. Deep operation.
In addition, each machine requires more than a dozen engineers to operate. The department emphasized that "there is a 24/7 monitoring system to collect real-time data during the construction process to improve safety and construction efficiency."
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