新型灾害冻震震害分析及形成机理

Damage evaluation and seismological mechanism of frostquakes

冻震是一类新型的自然灾害,其震感及震颤特征与一般构造型破坏性地震前兆现象相似,易造成人们的恐慌,也给工程设计人员带来担忧。目前国内外尚未提出相关数学模型描述冻震的形成机理、定量评估冻震震害水平,国内的相关报道甚至将冻震与冰震混淆。该文统计了已有的冻震记录,并基于能量假定估算了冻震可能达到的最大烈度及其地面峰值加速度(peak ground acceleration,PGA)。理论研究表明:冻震最大可能达到的修正Mercalli烈度(modified Mercalli intensity,MMI)为VI度,对应的地面峰值加速度低于典型构造型破坏性地震Elcentro-NS纪录的PGA的10%,冻震可能导致一般城镇钢筋混凝土建筑结构损伤开裂,但不会导致不可恢复性破坏。

The frostquake is a new kind of natural hazard. It shares similar phenomena with the precursory events of large destructive earthquakes. This has caused wide panic of the damage that frostquakes may bring about, and hence placed increasing importance on damage evaluation for the {rostquake. However, no scientific theory has been developed for mechanism explanation and quantitative damage evaluation of frostquakes in previous studies. An amount of Chinese reports even confound the frostquake with the icequake. In this paper, a series of available frostquake reports in the literature have been reviewed and discussed. Based on this review, the maximum intensity and highest peak ground acceleration （PGA） level of the frostquake is evaluated by adopting the elastic deformation assumption and conservation of energy assumption. The proposed theory predicts that the possibly maximum intensity of the frostquake is VI modified Mercalli intensity and its possibly highest PGA exhibits lower that 10 percent of that of earthquake elcentro-NS, which is a typical tectonic destructive earthquake. It is concluded that the frostquake effect may cause crack opening but no destructive damage in general reinforced concrete civil facilities.