Fifty years ago, a terrifying landslide occurred on Po Shan Road in the mid-levels. The debris flow rushed towards the 12-storey Xu Wo Building. The building collapsed immediately, and the top four floors of the new building next to it were also "cut off". 67 dead and 19 wounded.
This month, the Geotechnical Engineering Office held a special exhibition on the commemorative activities of "Reviewing History, Thinking about Danger in Times of Peace: 50 Years of Landslide 618". It is hoped that the public can improve the mountain by revisiting the two severe disasters in 1972 and understanding the current operation of the Po Shan Drainage Tunnel. Awareness of disaster prevention for mudslides.
On June 18, 1972, two shocking landslides occurred in Hong Kong. Before the accident, Hong Kong had rained heavily for three consecutive days. At noon that day, a reclamation site was located on Tsui Ping Road and Hiu Kwong Street in Kwun Tong. Due to the loose soil quality on the slope, the mud slipped and poured down. In a few seconds, tons of land mud buried the wooden houses of "Jiliu" in the Sau Mau Ping Temporary Resettlement Area. Since it was a Sunday, many citizens stayed at home, and more than 100 residents He was buried alive on the spot, resulting in a tragedy of 71 dead and 52 injured.
Po Shan Road landslide kills 67
Misfortunes do not come singly. By nearly 9pm, a serious landslide occurred on Po Shan Road in the mid-levels. A rocky hillside was severely weathered and slid, causing a two-storey house on Po Shan Road and a six-storey building on Conduit Road to fall. It was washed away, forming a mudslide, and then rushed towards the 12-storey Xuhe Building. The building collapsed and spread to the adjacent Jingcuiyuan Block E, which had not yet been occupied. The top 4 floors of the building were "cut away". Police, firefighters, civilians The security team even arrived at the scene overnight to rescue the injured. The next day, they rescued Li Xianlun, who later became the former permanent judge of the Court of Final Appeal. The natural disaster eventually resulted in 67 deaths and 19 injuries.
The Deputy Director of Geotechnical Engineering Office (Hong Kong Island) of the Civil Engineering and Development Department, Cheung Bing-yip (left), and Chief Geotechnical Engineer/Slope Safety Lui Lok Sum pointed out that there are still more than 300 landslides in Hong Kong every year, and urged the public not to take it lightly.
(Photo by Li Zetong)
Zhang Bingye, Deputy Director of the Geotechnical Engineering Office (Hong Kong Island) under the Civil Engineering and Development Department, pointed out that after these two horrific natural disasters, the Government decided to set up the Geotechnical Engineering Office in 1977 to deal with the dangerous slopes in Hong Kong, so as to avoid a repeat of the tragedy.
The investigation report revealed that the high water level in the Baoshan area led to the instability of the mountain
The Sau Mau Ping Memorial Park, which is currently adjacent to Tsui Ping Road, Hiu Kwong Street and Hiu Ming Street, commemorates the 71 residents of the resettlement area who were buried alive on that day.
As for the Po Shan Road landslip incident, the GEO's report of the Rain Disaster Investigation Committee later pointed out that the accident was caused by the lack of strict supervision of the construction site under the landfill, resulting in the high water level in the Mid-Levels Mountains. On rainy days, the water level will rise, making the mountain unstable.
Zhang Bingye said that in view of this, the Geotechnical Engineering Office installed 73 drainage pipes with a total length of 90 meters in the Po Shan area between 1984 and 1985 for drainage purposes.
However, by the early 2000s, monitoring data showed a downward trend in the discharge of these lateral drains, causing the groundwater level to rise to higher levels at local locations during heavy rains.
In order to regulate the water level in the Baoshan area, the Geotechnical Engineering Office designed a sustainable groundwater level regulation system, the Baoshan Drainage Tunnel, which was opened in 2009.
(Photo by Development Bureau)
Due to the increasing number of extreme weather in recent years, the risk of landslides brought by natural hillsides has also increased. It is necessary to take precautionary measures to ensure slope safety.
Chief Geotechnical Engineer/Slope Safety Lu Lexin pointed out that the Po Shan area is affected by high groundwater level and unfavorable geological conditions. If the water level is too high, landslides will easily occur, but if the water level is too low, nearby buildings will be prone to subsidence.
To regulate the water level in the area, the Geotechnical Engineering Office designed a sustainable groundwater level regulation system, the Baoshan Drainage Tunnel, which was opened in 2009.
The Po Shan Drainage Tunnel consists of two drainage tunnels and 172 inclined drainage pipes, and is equipped with an automatic real-time groundwater monitoring system, which can regulate the groundwater level in the Po Shan area, thereby reducing the risk of large-scale landslides.
(Photo by Li Zetong)
The Po Shan Drainage Tunnel consists of two drainage tunnels and 172 inclined drainage pipes, and is equipped with an automatic real-time groundwater monitoring system, which can regulate the groundwater level in the Po Shan area, thereby reducing the risk of large-scale landslides.
(Photo by Development Bureau)
Using new technology to dig tunnels and monitor water pressure
Lu Lexin said that the design of the drainage tunnel was novel, and many challenges were encountered when excavating it.
The Po Shan Drainage Tunnel consists of two drainage tunnels with a diameter of 3.5 meters respectively and a total length of 500 meters. The engineering staff used the technology of "upper punching hammer" for the first time in Hong Kong, and specially introduced a retractable tunnel boring machine. When drilling a tunnel is completed, it can be retracted to its original position, and then another tunnel can be drilled, saving the need to dig a shaft at the end of the tunnel to retrieve the drilling machine. Destruction of natural hillsides.”
The Po Shan Drainage Tunnel consists of two drainage tunnels with a diameter of 3.5 meters respectively and a total length of 500 meters. The engineers used the technology of "upper punching hammer" for the first time in Hong Kong, and specially introduced a retractable tunnel boring machine. When finished drilling a tunnel, it can be retracted to the original position to drill another tunnel, eliminating the need to excavate a shaft at the end of the tunnel to retrieve the drilling machine.
(Photo by Li Zetong)
In addition, engineers laid 172 inclined drainage pipes in the narrow tunnel, the longest inclined pipe is 100 meters long, and is equipped with an automatic real-time groundwater monitoring system.
In recent years, through digital twin technology, the water level data measured by the hydrometer can be sent back to the virtual model, and the "twin" in the virtual world can be used to display the water level change, and monitor the groundwater level in the Baoshan area around the clock. If the water level is too high, It will also automatically open the drain valve to speed up the drainage of the groundwater level. Lu Lexin revealed that the drain valve can also be operated manually, "Some water pipes are easy to exceed the standard. Set a switch, and when the rain stops, it will come back.”
In order to comply with the principle of multiple uses for one site, the Po Shan Drainage Tunnel set up a "Landslip Technology Exhibition Hall" last year, which is open to the public, schools or groups to make appointments for guided tours, hoping to educate the public on the importance of slope safety.
(Photo by Li Zetong)
The drainage tunnel was used for filming
In order to comply with the principle of multiple uses for one site, the Po Shan Drainage Tunnel set up a "Landslip Technology Exhibition Hall" last year, which is open to the public, schools or groups to make appointments for guided tours, hoping to educate the public on the importance of slope safety.
Lu Lexin pointed out that the drainage tunnel is divided into four areas, including the Po Shan Disaster Memorial Hall, the Climate Change Impression Hall, the Landslip Knowledge Gallery and the Drainage Tunnel Experience Gallery. Some clips on climate change and slope safety also use augmented reality (AR) to show the condition of drains.
Lu Lexin revealed that there are an average of 3 to 4 guided tours every month, and he also cooperated with TV stations to film and explain the situation of the drainage tunnel. There's a lot of atmosphere."
Coinciding with the 50th anniversary of the Po Shan Road landslide accident this year, the Geotechnical Engineering Office will hold a commemorative event "Reviewing History, Be Prepared in Times of Peace: 50 Years of Landslide 618" from 3rd to 6th this month at the Exhibition Room of F Warehouse, Tai Kwun, Central Special exhibition.
There are several experience zones and workshops in the exhibition, including a 4D landslide virtual reality experience zone, where participants can experience the situation of the Sau Mau Ping Temporary Resettlement Area being covered by hundreds of tons of land mud from a first-person perspective of squatters.
As for the STEM area, there is a "Smart Sandbox - "Dam" to block you", through the smart sandbox, you can experience the mud-rock dam to intercept the landslides on the natural hillside.
From the 24th to the 27th of this month, the exhibition will be moved to the second phase of the new city center in Tseung Kwan O.
Zhang Bingye and Lu Lexin mentioned that since there are still more than 300 landslide incidents in Hong Kong every year on average, the survey indicated that more than 70% of the respondents believed that the slopes in Hong Kong were safe, and only less than 20% of the respondents believed that it would still happen in Hong Kong. Large-scale landslides, we appeal to the public not to take it lightly. On weekdays, people should avoid approaching hillsides marked with landslide risk signs. If you unfortunately witness a landslide, you should immediately go to a safe location and call the police for help.
Mid-level Baoshan Drainage Tunnel Innovative technology to reduce the risk of landslides Built-in exhibition hall to record the history of blood in the 618 rainstorm half a century ago
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