汶川地震溃坝险情土石坝烈度分布及震害特征

Intensity distribution and characteristics of severely damaged earth-rock dams induced by Wenchuan Earthquake

通过对汶川地震中69座溃坝险情土石坝所处烈度区及其实际震害情况的调查、统计和分析,研究了土石坝震害类型、破坏程度与所在烈度之间的关系,认为汶川地震中土石坝震害随烈度变化的规律性显著。分析表明,Ⅵ度以下烈度区土石坝没有溃坝险情发生。在Ⅵ度至Ⅸ度烈度区,随着烈度等级的增加,震害种类及其震损程度随之增加,在不同烈度区影响坝体安全的震害的种类不同。坝体裂缝是溃坝险情土石坝最普遍的震害形式,坝体贯穿性横向裂缝多见于Ⅸ度烈度区,溃坝险情土石坝在Ⅵ,Ⅶ,Ⅷ,Ⅸ度烈度区内表现出的震害类型和危险程度有所差别。认为在土石坝抗震设计和应急救援中应认识到这些震害特点以减少震后由于溃坝造成次生灾害的发生。

The relationship between the damage types and levels of earth-rock dams in different seismice intensity regions is studied. Based on survey and statistic analysis of 69 severely damaged earth-rock dams induced by Wenchuan Earthquake, the occurrence of seismic damage is closely related to the seismice intensity. The data show that there is no severely damaged dam in the areas which are less than VI level of seismic intensity. With the increasing intensity level, the damage types and levels of dams increase. There are different damage types in different intensity zones, but dam cracks are the most common form. Serious horizontal penetrating cracks are the main threat to dams in IX level intensity. The damage types and risk levels of severely damaged dams in different intensity zones are different. The seismic design and emergency rescue should be aware of these characteristics to reduce the secondary disasters caused by dams failure during earthquakes.