地震大型滑坡滑带岩体结构特征及地质原型分析

以汶川地震触发最大滑坡-大光包滑坡为例,基于现场工程地质调查、槽探、平硐,室内SEM电镜、岩石薄片技术手段,分析地震大型滑坡滑带岩体结构特征及地质原型。结果表明,大光包滑坡滑带岩体一方面遭受了严重构造碎裂,表现为:充填胶结裂隙发育,岩体呈紧密镶嵌的角砾结构和基底式胶结结构,厚度上呈现分带特征;另一方面还发育大量新裂隙,表现为:新鲜裂隙平顺、无充填,具有张性特征,延伸长度短、间距小,优势发育在几乎水平和垂直两方向。通过对显微裂隙分期配套和里德尔裂隙解译,揭示大光包滑坡滑带地质原型为层间构造错动带,地震中大光包滑坡在该带内发生了剪切破坏。

ROCK STRUCTURE AND GEOLOGICAL CHARACTERISTICS OF THE SLIDING ZONE OF EARTHQUAKE-INDUCED LARGE LANDSLIDE

Based on geological investigation and micro-analysis, the earthquake-induced large landslide was studied by taking the Daguangbao landslide as a case. The results show that the sliding zone of the Daguangbao landslide was heavily disturbed by historical tectonic event. The rock was characterized by mosaic breccia with a lot of cemented cracks. A large number of fresh cracks with small spacing and short in length. The dominant directions of these fresh cracks were almost in horizontal and vertical. The cross-cut relationship of the calcite veins and Riedel shears were used in geological analysis. It was found that the shear zone of the Daguangbao landslide was formed in a bedding fault which occurred shear failure during the Wenchuan earthquake.