Seismic damage and behavior analysis of earth dams during the 2008 Wenchuan earthquake, China

The May 12, 2008, Ms 8.0 Wenchuan great earthquake, China caused earthquake damages of 2666 earth dams, these damaged dams are in medium and small scale, located in 8 provinces or municipalities, of which 69 dams were at dam-break risk, and 331 were at high-risk. There were 1996 damaged dams located in Sichuan Province, including all the 69 at dam-break risk and 310 at high-risk. Through a detailed scientific investigation, earthquake damage and emergency data were collected, and the isoseismal map of Wenchuan earthquake, with damaged dams marked on it, was given. Also distribution feature of the above 69 dams along the fault zones were discussed. Typical damage types of earth dams were analyzed. And the action of rare great earthquake, poor quality of dam construction, adverse running state of earth dams before earthquake, and frequent aftershocks were concluded as four main reasons of dam damages. Taking 147 dams with complete geometric parameters as statistical samples, some empirical graphic formulas were proposed, to make rapid evaluation of damage degree. Finally, some useful practical measures were provided, to serve the post-earthquake emergency danger removal, also it may improve the seismic performance of dams. In view of the insufficiency of local geology, site effect and soil property data of damaged dams, application of the qualitative results and empirical relationships to other sites, should be very prudent.