Hangzhou Metro responds to site flooding due to lake overflow
Expert: There may be a gushing due to the shock at the bottom of the lake
On the afternoon of May 18, a large amount of stagnant water appeared at Jinshahu Station of Hangzhou Metro. Line 1 of Hangzhou Metro stopped temporarily at Jinshahu Station and was temporarily closed.
The live video showed that there was a water leak on the top of the platform of Jinshahu Station of Hangzhou Metro. After the water spread to the platform, it flowed to the subway tunnel.
A Hangzhou citizen said that when Metro Line 1 passed Jinshahu Station, she could clearly see the water dripping from the top of the platform to the carriage. When she evacuated from the carriage and exited the subway entrance, the water level was as high as her knees.
On the afternoon of the 18th, a reporter from the Chengdu Business Daily-Red Star News learned from the Hangzhou Metro that the cause of the accident was a pipe surge in the sunken plaza of Jinsha Lake Park at 3 p.m. that day, and the overflow of the lake caused waterlogging in Jinsha Lake subway station.
At 11 o'clock that night, the "Qiantang Announcement" announced that the cofferdam at the leaking place in Jinsha Lake Park had been built, and the subway station had stopped entering water.
On May 19, according to the official news of Hangzhou Metro, Metro Line 1 has resumed operation, and Jinshahu Station resumed operation at 17:30.
A relevant person from the operator, Hangzhou Hanggang Metro Co., Ltd., said that the accident report will be officially released.
Official: The lake is overflowing and no one is trapped
It is understood that Hangzhou Metro Line 1 is the line from Xianghu Lake to Xiaoshan International Airport, with 33 stops in the whole process, passing through 5 areas including Xiaoshan District, Binjiang District, Shangcheng District, Gongshu District, and Qiantang District.
On May 18, passenger Mr. Li got on the bus from "Fengqi Road Station" as usual, and planned to transfer to "South Wennan Road Station", passing through "Jinsha Lake Station" in the middle.
Mr. Li recalled to reporters that in the evening, when the carriage was traveling, suddenly only "Jiuhe Road" was lit on the display screen, and the rest of the stations were darkened.
Many passengers around him looked at the station display screen from time to time, and he realized that the change of the display screen was notifying passengers to adjust the operating route.
Because Jinshahu Station was affected by flooding, many passengers were arranged to get off at "Jiuhe Road" four stops before Jinshahu Station.
Mr. Li said that he got off at Jiuhe Road Station at around 19:20. The broadcast in the subway platform broadcasted the adjustment of the operation line. There were many more staff in the station than usual, guiding passengers to Exit A to take the shuttle. car.
When leaving the station with the people, Mr. Li saw the shuttle buses coming one by one, "Everyone was in an orderly manner after getting off the bus, and I saw that the passengers were calm. There were about 10 vehicles at the scene, and I was waiting. It took two or three minutes to get on the train." Mr. Liang, a citizen who also got off at Jiuhe Road, told reporters that the flow of people outside the subway station was comparable to the "Spring Festival".
Mr. Li saw on the shuttle bus that a large number of people gathered on both sides of the road, and the flow of people probably stretched for more than 200 meters.
At 7:45 p.m. on the 18th, the "Qiantang Release" official Wechat announced that at 3 p.m. on the 18th, there was a pipe gushing in the sunken plaza of Jinsha Lake Park, and the overflow of the lake caused the Jinsha Lake subway station to form a flood.
Relevant departments immediately organized emergency repairs, carried out pipe plugging and drainage of accumulated water, and all the on-site personnel have been evacuated, and no one was trapped.
Expert: Piping may cause shocks at the bottom of the lake
How did this surge come about?
Many Hangzhou residents believe that it may be caused by construction nearby.
According to local citizens, there is an artificial lake in Jinsha Lake Park, which was completed at the end of December last year and has not yet been officially opened to the public.
A senior subway engineer in South China told reporters that construction is only one of the possibilities for piping, but so far, there have been no related reports of construction nearby.
The engineer pointed out, "Generally speaking, without mechanical disturbance, the soil can maintain a state of equilibrium. If there is construction nearby or mechanical vibrations that cause some disturbance to the soil, it may cause piping."
The engineer introduced that when repairing the subway, a foundation pit is usually dug around the subway to make an underground continuous retaining wall, or a retaining pile with a spacing of 1 to 1.5 meters is built, and concrete is sprayed through the fixed mesh in the middle. It only has a slight soil-retaining effect and has no waterproofing effect.
"According to the on-site video and reports, the possible reason for the piping is that the bottom of the lake vibrated, and the water flow carried the sediment to the sinking square. Due to the terrain, after the lake water flowed into the sinking square, it passed through the building in the sinking square. The subway entrance and exit flow into the subway station.”
Professor Huang Guoru of South China University of Technology introduced to reporters that the simple understanding of plumbing generally refers to embankment plumbing.
The flow velocity of underground seepage is very slow, and the soil will form pores.
The increase in the flow rate of water in the pores will cause the phenomenon that the fine particles are washed away, causing the water to gush.
"The hazard of piping is that the sluice, foundation and soil framework of the embankment will be damaged, and then hollowed out, causing the building to collapse, resulting in serious embankment and dam failure."
Professor Huang Guoru pointed out, "It's not a case of subway flooding every summer. Some pipes are relatively slow. After a long time, after the soil is washed away, the water will flush out. The terrain of the sinking square is relatively low, and there is soil below, which may be the foundation. Problems, but the foundation leakage will not leak so much, and the specific situation needs on-site analysis."
Chengdu Business Daily-Red Star News Reporter
Cai Xiaoyi Pan Junwen intern Zhu Yue Yang Yun
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