Surveillance cameras captured the moment a section of a road collapsed, with retaining walls plunging to the ground, in south-west China’s Sichuan province.
Video shows the road was empty at the time and no causalities were reported.
The road was located near the entrance and exit of an underground parking lot in the city of Guang’an.
An eyewitness told Chinese media that a section measuring at least 50m in length caved in.
Authorities are investigating the cause of the collapse, but some media outlets reported it was due to days of rain.
Image via BBC
Yes, rain-water could have eroded the earth below the asphalt pavement and the other possible reasons could be lack of maintenance or poor quality.
Taking into consideration all the structural fills, it seems like after the road construction, the top was not filled, compacted, and sealed properly. When major roads are constructed via an entrance and exit of an underground parking lot, there are usually two methods of construction.
One is cut and fill. Cut the ground, make the cut via the underground parking structurally compacted and sealed with structural fills. Or bore through the soil if granular soil grades (with a Tunnel Boring Machine (TBM). If it is cut and fill method for the road, the structural filled at the top need to be coarse aggregate of medium size, well compacted. That seems to be the only possibility to achieve structural fills.
Another possibility is that there could have been a well or sink-holes there which collapsed the road. Reconstruction of the road will immensely based on safety – dig and go down to destabilize the ground with short-Crete the soil and safety in mind before initiating and measures taken to avoid accidents due to reconstruction.
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