Judging from the damage forms of bridges in some strong earthquake areas, the earthquake damage of bridges is mostly due to bank slope sliding, bridge head sinking, pier displacement to the center of the river, bridge opening shortening and pier fracture. Some piers are displaced or inclined due to the settlement of pier foundation; Or the change of pier causes the bearing to tilt, fall and fall off the beam.
5. 12 Wenchuan earthquake geological disaster
5. 12 Wenchuan earthquake geological disaster
5. 12 Wenchuan earthquake geological disaster
5. 12 Wenchuan earthquake geological disaster
Bridges are the control nodes in the highway network. Once the bridge is damaged, it takes a long time to repair and load construction equipment. Therefore, the damage of many bridges in the disaster area has seriously delayed the rescue work. According to the data released by the Ministry of Communications of China, as of June 6, 2008, the Wenchuan earthquake had damaged 4,840 bridges and affected 98 tunnels in Sichuan, Gansu, Shanxi, Chongqing, Yunnan and Hubei provinces.
The failure mode of some bridges in the epicenter area shows that most of the bridges damaged by earthquake are caused by embankment landslide, abutment sinking, pier displacement towards the river, bridge span shortening and pier fracture. Some are caused by the subsidence of pier foundation, which leads to the displacement or inclination of bearings, while others are caused by the deformation of piers, which leads to the inclination and collapse of bearings and the subsidence of bridge deck.
5. 12 Wenchuan earthquake geological disaster
In this Wenchuan earthquake, there are two main reasons for the damage of bridges-the damage caused by foundation damage and the damage caused by strong vibration of bridge structure. In addition, the bridge was destroyed by mountain collapse and burial.
In Wenchuan earthquake, there are two main reasons for bridge damage. One is the bridge damage caused by the foundation damage. The second is the bridge damage caused by the destructive vibration of the bridge structure. In addition, the bridge was destroyed and buried by landslide debris.
North; Juanjiang Bridge in Chuan County collapsed as a whole, and the main deck of Qianjiang No.9 Bridge collapsed.
Bridge collapse in Chenjiaba Town, Beichuan County
■ Severe deformation of bridge foundation, pile cap and pier ■ Serious deformation of bridge embankment, pile cap and pier.
Due to the destruction of earthquake force level, the whole bridge foundation moves sideways, or the cap and pier are seriously deformed, which leads to the fall of the protective layer of steel bars and the exposure of steel cages. Due to the horizontal force of vibration, the bridge foundation is horizontally displaced, or the platform and pier are seriously deformed, which leads to the peeling of protective concrete and the exposure of steel bars.
5. 12 Wenchuan earthquake geological disaster
The bridge stop is a cracked and crushed bridge deck shear key.
Slope collapse behind abutment
The collapsed bridge deck and its temporary access road in Nanba Town, Pingwu County, city.JPG, and the damaged bridge and temporary traffic access road in Nanba Town, Pingwu County.
This is because the horizontal seismic force of the bridge leads to the decline of the deck.
■ The beam-slab bridge is seriously damaged.
■ Most of the beam bridges are damaged.
The piers of bridges in disaster areas are mostly flexible piers, which use pile foundations to basically resist earthquake forces. However, the pile-free abutment and subgrade slope protection are often destroyed, resulting in bridge beam falling and lateral displacement.
Flexible piers and pile foundations are widely used in bridges in disaster areas to resist earthquake forces. However, bridges without pile foundation and embankment protection are easy to be damaged, especially when the bridge deck sinks and is horizontally misaligned.
■ The arch bridge is slightly damaged.
■ The arch bridge is relatively less damaged.
In this earthquake, the single-hole long-span reinforced concrete arch bridge performed well, and there was no major damage, and the damage of two-span or multi-span arch bridges was relatively light.
In the Wenchuan earthquake, the long-span single-hole reinforced concrete arch bridge performed well without major damage. The damage degree of two-span or three-span arch bridge is relatively low.
5. 12 Wenchuan earthquake geological disaster
5. 12 Wenchuan earthquake geological disaster
A suspension bridge was twisted in the earthquake. A steel suspension bridge was twisted in the earthquake.
5. 12 Wenchuan earthquake geological disaster
5. 12 Wenchuan earthquake geological disaster
Chenjiaba collapse bridge
The collapsed bridge of Chengjiaba in Beichuan
Temporary and rapid construction of steel bridges to rescue damaged existing bridges.