Preliminary investigation shows the cause is leakage from the underground diaphragm wall at the construction site.

The night before last, at the northwest corner of the intersection of Fuchun Road and Chengxing Road in Hangzhou Qianjiang New City, a large sinkhole appeared again on the road surface.

Why "again"? Because in May this year, at the same location, a road surface subsidence had also occurred.

Driving at night, a large sinkhole suddenly appeared ahead

Around 9 pm the night before last, Ms. Zhong, a Hangzhou resident, was driving to the intersection of Fuchun Road and Chengxing Road and waiting at a red light when she suddenly saw white smoke rising from the road ahead. Shortly after, she noticed the road surface began to sink, and at the same time water kept gushing up from the sinking area.

"The whole process lasted about 10 minutes, and then someone called the police," Ms. Zhong said. "Fortunately, no people or vehicles were trapped by the road collapse at that time."

Yesterday morning, when the reporter arrived at the scene, the collapsed road surface had been enclosed with barriers and covered with soil. The entire collapsed area was visually estimated to be about four to five hundred square meters. Several cracks had also appeared on the road surface near the barriers, with the widest crack about 1 centimeter. Maintenance workers were inside the barriers using instruments to measure the collapsed road surface.

Road subsidence caused by leakage from underground diaphragm wall

Next to the collapsed road surface is a construction site contracted by Kunlun Construction.

Mr. Xu, project manager of the construction site's project department, said the road subsidence was caused by leakage from the underground diaphragm wall.

An underground diaphragm wall is a continuous reinforced concrete wall built underground, used for water cutoff, seepage prevention, load bearing, and water retention. It is generally suitable for building basements, underground shopping malls, parking lots, underground oil depots, deep foundations of high-rise buildings, etc.

So why did the underground diaphragm wall suddenly leak?

Manager Xu explained that this was because during construction of another project, a passage was drilled underground, and this passage penetrated more than 2 meters into the underground pile foundation of the construction site, thus causing leakage from the underground diaphragm wall.

Due to the leakage from the underground diaphragm wall, mud and sand under the subsided road section were lost, thereby causing the road surface to subside.

During the closed construction period, avoid Fuchun Road when heading toward Binjiang

Because the road subsidence affected normal road traffic, the traffic police department immediately adopted temporary traffic control measures.

Chengxing Road (Shimin Street–Fuchun Road section) is one-way west to east. Those going east to west on Chengxing Road can turn left at the intersection onto Fuchun Road, then use the small circulation via Shimin Street to return to Chengxing Road.

Fuchun Road (Xiangzhang Road–Chengxing Road section): motor vehicles are prohibited from passing north to south, while non-motor vehicles are still allowed. Vehicles traveling north to south along Fuchun Road must detour via Xiangzhang Road–Wuxing Road–Chengxing Road, that is, go around Qianjiang New City Forest Park once before returning to Fuchun Road.

At the same time, Fuchun Road, as a main road in Qianjiang New City, also carries considerable traffic to and from Qianjiang Third Bridge. Judging from yesterday's daytime traffic conditions, the pressure was not very great. But today is a workday, and due to the closed road construction, traffic pressure may increase sharply.

Therefore, the traffic police also remind car owners that in the coming days, when going from Binjiang toward the city, they can still choose Fuchun Road, because south-to-north traffic is currently no problem.

For those going from the city toward Binjiang, car owners are advised to avoid Fuchun Road and take the parallel Zhijiang Road or Qianjiang Road instead, which would be a better choice.

In May this year, subsidence also occurred at the same intersection



Starting May 17 this year, subsidence appeared on the sidewalk at the northwest corner of the intersection of Fuchun Road and Chengxing Road, right next to the construction site of Kunlun Construction. The cause of the subsidence was improper construction of the deep foundation pit, which caused water seepage and led to soil and water loss.

The next day, nearly 24 hours after discovering the subsidence problem, Kunlun Construction reported the situation to the traffic police, and the road subsidence escalated into a road collapse.

By May 19, the collapsed area had extended from the non-motor vehicle lane and green separation belt to the motor vehicle lane, and a large pit of about more than 100 square meters appeared at the scene.

On May 20, cracks on the Fuchun Road surface increased and widened, and the collapsed area further expanded. The underground sewage pipes and tap water pipes at the collapse site were affected.
After more than a week of emergency repairs, the subsided area was restored to its original appearance.