In recent years, road collapse has become a major geological disaster in China's cities. Road collapse has occurred in all major cities in China, which not only poses a threat to our people's lives, but also causes road operation interruption, traffic congestion, water supply and drainage pipelines and telecommunications pipelines rupture, resulting in greater social impact. Because it involves various municipal infrastructures and multiple administrative departments, it is also difficult to deal with. The sidewalk in Chongqing suddenly collapsed, not necessarily because the soil under the sidewalk was hollowed out, but for various reasons.

For the sudden collapse of the sidewalk, the reason why the soil below is hollowed out may be affected by extreme precipitation weather. In recent years, the continuous precipitation in the Yangtze River basin in China has caused great pressure on underground drainage facilities, and long-term precipitation has led to sidewalk collapse. Affected by natural geology, there may be natural caves under urban roads. Some cities have a long history, which may retain the old ditches left by the ancient cities, or there may be some abandoned air-raid shelters and other caves. These areas are uninhabited all the year round, and under the action of water, a large amount of soil flows into caves, forming a large area of cavities.

Affected by the side construction. If the underground pipeline is not backfilled after construction, the soil will become loose. Under the influence of groundwater, vehicle vibration and other factors, quicksand erosion is easy to occur, forming cavities on subgrade, and eventually leading to road collapse accidents. The construction of subway tunnel, including shield tunnel and shallow excavation method, may cause stratum disturbance, a large amount of groundwater seeps out, so that a large amount of sediment in the upper or surrounding loose soil layer is taken away, gradually forming cavities, resulting in pavement collapse. Building dewatering is a method often used in underground facilities construction. Due to the design and construction problems of the construction dewatering well, in the long-term pumping process, the fine soil in the stratum is taken away, which breaks the original soil balance and gradually forms a cavity. When the upper soil support is insufficient, the pavement will collapse.