Recently, the approach bridge of the Hongqi Super Bridge collapsed in Markang City, Aba Prefecture, Sichuan Province, attracting widespread attention.Jilin-1 Gaofen 03D53 satellite specially took a set of high-definition images while passing through Aba, Sichuan, clearly recording the scene after the bridge collapsed.
The Hongqi Super Large Bridge is located in Markang City, Aba Prefecture, Sichuan Province. It is part of the highway reconstruction project in the Shuangjiangkou Hydropower Station reservoir area, with a total length of 2.6 kilometers.
The main bridge adopts PC continuous steel structure, and the approach bridge adopts prefabricated prestressed concrete T-beams. The main pier is 172 meters high, and a high pier structure is used to adapt to the canyon terrain.
Satellite images show,There is an obvious landslide on the west side of the bridge, which highly coincides with the location of the bridge collapse area, clearly showing the connection between geological disasters and bridge damage.
As you can see,The approximately 130-meter-long approach bridge has fallen into the Ashimuzu River below, and the signs of collapse left at the scene are clearly visible, but the main bridge structure remains intact.
According to official reports and expert analysis, the bridge collapse was caused by the superposition of multiple factors.
The Hongqi Super Large Bridge is a highway reconstruction project in the Shuangjiangkou Hydropower Station reservoir area. The mid-span closure was completed on January 14 this year, less than 10 months after it was opened to traffic.
As a facility surrounding the reservoir area, the area where the bridge is located was affected by the first impoundment of the hydropower station. After the mountain was repeatedly soaked by water levels, the strength of the rock and soil mass decreased, forming a "reservoir bank reconstruction" effect.
The so-called reservoir bank reconstruction refers to the phenomenon that during the formation and operation of the reservoir, the action of the reservoir water causes the stability of the bank slope rock and soil to change, causing deformation and destruction. It is an important research content in the discipline of hydraulic engineering. The formation mechanism mainly includes water saturation of the bank slope rock and soil, changes in underground water pressure, dynamic and static water pressure fluctuations caused by water level rise and fall, and wave erosion.
at the same time,Although the 172-meter-high main pier of the bridge is adapted to the canyon terrain, it has weak resistance to lateral forces.
also,The Western Sichuan Plateau itself is geologically fragile, and this year's cumulative rainfall in the region has further aggravated mountain instability.
The superposition of this series of factors eventually caused a landslide of more than 3 million cubic meters, shearing the pile foundations of the bridge piers and causing the approach bridge to collapse.
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