极震区岩体地震动力破坏若干问题探讨

Discussion on seismic failure of rock mass in meizoseismal areas

汶川地震时极震区产生了严重的地震地质灾害,其中强烈地震动造成的岩体动力破坏是造成灾害的根本原因。从极震区含义、地震动特征、岩体地震动力破坏概念、地震松动岩体和方法论等方面初步探讨了极震区岩体地震动力破坏问题。极震区是未来地震的潜在震源区,区内的地震属于直下型。极震区地震动具有不同于非极震区的地震动特征,岩体地震动力破坏的复合性特点就是地震动的不确定性造成的。对极震区岩体动力破坏概念的理解应考虑地震动的特点。地震松动岩体是极震区地震动造成的一种特殊破坏类型,是形成震害次生灾害的重要原因。岩体工程地质力学等学科的思想方法和技术手段为研究极震区岩体地震动力破坏这一命题提供了良好的基础,预测和评价极震区因岩体动力破坏造成的工程震害和地质灾害,减轻和预防未来地震时的灾害损失,是极震区岩体地震动力破坏研究的目标和方向。

Tremendous geological hazards are induced by strong earthquake at the meizoseismal area of the Wenchuan Earthquake,May 12,2008.The rock mass seismic failures caused by strong ground motions are mainly responsible for that.The problem of rock mass seismic failure under ground motions at meizoseismal area is discussed regard of meaning of meizoseismal area,characteristics of ground motions,definition of rock mass seismic failure,seismic dynamo-relaxed rock mass and methodology.Meizoseismal area is a potential earthquake region of the future earthquake,in which the direct-underground earthquake would happen.The ground motions at meizoseismal area have some characteristics totally different from that outside of the meizoseismal area.It is significant to understand the meaning of rock mass seismic failure at meizoseismal areas considering the nondeterministic characteristics of ground motions.Seismic dynamo-relaxed rock mass is a special type of rock mass seismic failure at meizoseismal areas damaged by ground motions,and it is an important factor causing secondary hazard after earthquakes.The concepts,methods and techniques of related subjects such as rock mass mechanics,engineering geology etc.,have laid a good foundation for studying rock mass seismic failure under ground motions at meizoseismal areas whose tasks and aims will be to predict and assess engineering earthquake damage and geological hazards induced by rock mass seismic failure as well as to reduce and to prevent the losses during the future earthquakes.