13.3 Xianghu Metro Station Collapse，Hangzhou，China...
Xianghu Station is the starting point of Hangzhou Metro Line 1.This station was constructed by using the bottom⁃up construction method in eight excavations from north to south.The collapsed position is the second excavation on the northern side（N2 excavation），which is near the junction of Fengqing Road and Xiangxi Road as shown in Figure 13.4.The excavation occupies a planned area of about 2 313 m2，with approximately 21.5 m in width and 107.6 m in length.The maximum digging depth is up to 16.2 m.The accident happened at the No.2 foundation pit as shown in Figure 13.5.The foundation pit is 107.8 m long and 21.05 m wide，and the depth is 15.7⁃16.3 m.
Figure 13.4 Plan view of the N2 excavation
At around 15：15 on November 15，2008，a large⁃scale collapse accident occurred on the west side of the North 2 foundation pit.The collapsed area was 75 m long，about 20 m wide and 15 m deep.More than 11 vehicles in progress fell into the collapsed area.At least 50 people were buried in the collapse，causing 21 persons dead and 4 injured，and the direct economic losses was more than 49.62 million yuan.This is the most serious accident in the history of China's subway construction.
On November 17th，2008，there was a crack on the ground at the southern end of the collapsed foundation pit.In order to facilitate the rescue work，the houses near the accident were completely knocked down.
Figure 13.5 Some site scenes of the accident