从郯庐地震带安丘地区地震成因土层构造认识地震破坏作用

Understanding failure functions caused by earthquakes on the basis of seism-genesis soil-layer structures in Anqiu area,Tancheng-Lujiang seismic zone

在郯庐地震带的安丘地区,发现始新世朱壁店组厚层冲积层中发育一些同沉积的地震扰动岩土层。通过野外观测和比较地震地质学研究,识别出了振动液化砂脉、液化砂墙、裂隙充填砂质卵石墙、震塌落体、地震层内断裂及地震沉陷构造等地震成因土层构造。它们是5～8.5级强烈地震事件的记录。根据这些强烈地震成因土层构造的动力学特征进行分析,认为强烈地震对地基土的破坏作用有几种方式:液化作用、地震裂隙充填作用、振动塌落作用、断裂破坏作用和震沉陷落作用。

Some syndepositionai soil-layers disturbed by earthquakes were discovered in thick-bedded alluviums of Eocene Zhubidian formation in Anqiu area of Tancheng-Lujiang seismic zone. Through the field observation and comparative seism-geologic studies, many seism-genesis soil-layer structures such as vibration-liquefied sand vein, vibration-liquefied sand dyke, sandy cobble dyke by fissure filling, seismic fail mass, seismic intra-layer fault and seism-settlement structures etc. were recognized. The seismic structures were records of earthquake events of magnitudes ranging from 5 to 8.5. According to the analysis of dynamic characteristics of these seismic soil-layer structures, it was proposed that failure functions of foundation caused by strong earthquakes included liquefaction, seismic fissure filling, vibration failing, fracturing and seismic settlement of soil.