Geotechnical Aspects of 2008 Wenchuan Earthquake, China

Abstract

The 2008 Wenchuan earthquake of China produced significant damage in the local community. Since the affected area was so vast, it became very difficult to apply previous experiences to the restoration of the community. The present paper concerns findings during technical visits to the damaged area and lessons for the future of the area. From the geotechnical viewpoints, this earthquake is characterized by many slope failures with a large range of size. Many landslide dams were formed as a consequence of big slope failures to be a threat to the downstream area. Smaller slope failures, that were much more in number, are important as well, because many local roads were destroyed by them and post-earthquake rescue and restoration activities were affected. It was interesting that different types of slope stabilization measures functioned to different extents, avoiding total collapse. Some retaining walls translated due to significant seismic earth pressure. Mountain slopes that were thus disturbed by strong seismic shaking will cause further problems in the coming decades. As have been experienced after big quakes at different places in the world, those slopes will produce further failures and debris flows, and affect safety of local communities and transportations. Finally, geotechnical problems other than slopes are discussed.

Appendix Second Author’s Experience

Although more than 1 year has passed after the quake, the shocking memory given by the Wenchuan Earthquake still gives me frequent stimulus to my motivation to engage in disaster prevention study. In May, 2008, I was doing my master course in Southwest Jiaotong University, Chengdu, Sichuan Prov. China. At 14:28, on May 12th, 2008, I was still in bed for taking a nap which is a common habit in Sichuan Province. The sudden and strong jump of my bed woke me up. After a few seconds I still blamed this was a shaking caused by the experiment inside nearby National Power and Traction Lab. With uproar and yell coming out from the inside and outside of my dormitory, my intuition told me this was not an easy shaking. Without caring how much clothes still covering my body, I jumped onto the floor. At this moment the ponderous but loud noise created by the left and right shaking of the building hustled running pace of mine and my roommates. We crashed out of the door, and ran and jumped at a desperate speed from the fifth floor to the first floor. When we surged out the gate of our dorm, there were still more than two seconds shaking. Shamefully to say that for me fear and excitement coexisted in this one and half minutes. I never thought about the catastrophic destruction caused by this big “shaking”, because this was my first time to experience a real and devastating earthquake.

Since Chengdu City was around 100 km away from Yingxiu County, and also the epicentre was out of Sichuan basin, the destruction in Chengdu was not severe and nearly no building collapsed. However for the sake of students’ safety, all the universities arranged students camp outside in open areas or stadiums. After a few days I got a chance as a volunteer to join the rescues work in Deyang City, and mainly involved in logistic works, including transporting and distributing disaster relief supplies. In this short 2 days I visited Shifang County, where ruins and bodies of victims were excavated from the collapsed buildings. It was the first time for me to realize what a catastrophic earthquake it was. At that time I had no tear for them. What I did was to focus my full strength on the voluntary rescue work.