宁夏海原8.5级地震诱发黄土滑坡的变形破坏特征及发育机理
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摘要
海原地震是我国黄土地区影响深远的大震,其诱发的黄土滑坡不计其数。对海原地震中黄土滑坡密集发育的西吉、海原、固原地区开展调研工作,研究强震作用下黄土滑坡的基本特征、破坏类型,以及该地区黄土地震滑坡密集发育的成因机理。西-海-固地区黄土地震滑坡具有集中发育、扎堆群发的分布规律,且易发生在坡高较低、坡度较缓、山梁单薄、地貌破碎的斜坡地带,并具有方向性和运动液化的特点;考虑黄土特殊的结构特征及动力特性,黄土地震滑坡的破坏类型可分为振动软化——剪切破坏、振动液化——流动破坏、振动崩塌破坏及震后蠕变破坏四种;西吉县西南部黄土地震滑坡密集发育是因为该区处于海原地震地壳破裂带的几何投影中心,并受该区岩土分布特、地貌特征,以及所遭受地震波频谱特征控制。
Haiyuan earthquake is one of the most important earthquaks that happened in loess region of China,which triggered innumerable loess landslides.Investigations are carried out to study the basic characteristics,breakage types and dense development mechanism of loess landslides triggered by Hai Yuan earthquake in regions of Xiji,Haiyuan and Guyuan,where loess landslides are densely developed.The landslides in those regions display a dense and group development orderliness,are apt to occur on slope with lower height and dip angle,thin mountain and fragmentizedphysiognomy,and show the definitedirection and movement liquefaction characteristics.Based on the especial structure and dynamical characteristic,breakage types of loess earthquake landslide should be reduced to four types as shear breakage for vibration soften,flow breakage for vibration liquefaction vibration landslip,and creep breakage after earthquake.And then,the reason of loess earthquake landslide dense development in region of Xiji county should be concluded that it is loacted on the geometry projection center of fracture zone of Haiyuan earthquake,cooperating with the distribution of stratum,physiognomy and frequency compose of earthquake wave encountered.
Haiyuan earthquake is one of the most important earthquaks that happened in loess region of China,which triggered innumerable loess landslides.Investigations are carried out to study the basic characteristics,breakage types and dense development mechanism of loess landslides triggered by Hai Yuan earthquake in regions of Xiji,Haiyuan and Guyuan,where loess landslides are densely developed.The landslides in those regions display a dense and group development orderliness,are apt to occur on slope with lower height and dip angle,thin mountain and fragmentizedphysiognomy,and show the definitedirection and movement liquefaction characteristics.Based on the especial structure and dynamical characteristic,breakage types of loess earthquake landslide should be reduced to four types as shear breakage for vibration soften,flow breakage for vibration liquefaction vibration landslip,and creep breakage after earthquake.And then,the reason of loess earthquake landslide dense development in region of Xiji county should be concluded that it is loacted on the geometry projection center of fracture zone of Haiyuan earthquake,cooperating with the distribution of stratum,physiognomy and frequency compose of earthquake wave encountered.
引文
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[3]白铭学,张苏民.高烈度地震时黄土地层的液化移动[J].工程勘察,1990(6):1-5.
[4]Sasaa K.The mechanism starting liquefied landslides and debrisflows[C]∥4th International Symposium Landslide.Toronto,1984:349-354.
[5]Sassa K.The mechanism of debris flows[C]∥11th InternationalConference on Soil Mechanics and Foundation Engineering.SanFrancisco,1985:1173-1176.
[6]Wang Lanmin.Analysis of loess seismic landslides under irregularseismic loading[J].proceedings of the First International Confer-ence on Seismology and Earthquake Engineering,1991(1):511-518.
[7]Wang Lanmin,Sun Chongshao,Yuan Zhongxia.Zonation on seis-mic geotechnical hazards in loess areas of China[M].Manual forZonation on Seismic Geotechnical Hazard(Revised Version),Technical Committee for Earthquake Geotechnical Engineering,TC4,ISSMGE,1999.
[8]Yuan Z X,Wang L M.Collapsibility and seismic settlement of lo-ess[J].Engineering Geology,2009,doi:10.1016/j.enggeo.2008.12.002.
[9]王家鼎.高速黄土滑坡的一种机理——饱和黄土蠕动液化[J].地质论评,1992,38(6):532-539.
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