川西雅江地区构造-岩石变形特征及其控灾机制

川西雅江地区发育系列复式背斜、复式向斜及其伴生断裂的褶-断式构造组合样式。受强烈构造改造,岩石变形主要呈现出柔性滑脱、顺层剪切、脆性弯折、沿结构面强卸荷、大位移错动、断层破碎以及褶皱劈理化等7类样式。构造-岩石组合塑造着该区域雅砻江展布与深切河谷的演化,而河谷演化与构造改造共同控制着区域滑坡、崩塌等地质灾害的发育与分布。不同的岩石变形样式孕育不同类型的地质灾害,而岩性组合关系控制地质灾害发育的规模。受砂岩板岩互层弯折变形的控制,斜坡主要产生倾倒弯折→拉裂→滑移→失稳破坏→堵塞河道或阻断道路等多阶段变形破坏模式,形成雅江地区滑坡灾害最主要的成灾模式。

Geological Structure and Rock Deformation Characteristics and Their Geohazard-Controlling Mechanism in Yajiang Area,West Sichuan

Structural patterns of compound anticlines and synclines with faults superimposed are widely developed in Yajiang area,west Sichuan.Due to intensive tectonic reworking,at least seven rock deformation types present in the study area,including flexible slippage,bedding shear,brittle bending,unloading along structural planes,large-scale dislocation,fault fracture and fold cleavage.Structural-lithologic assemblage has shaped the distribution of Yalong river and valley evolution.Meanwhile,the development and distribution of geohazards,e.g.,landslides and collapses,and their stability and risk are controlled by valley evolution and tectonic reworking.The different of geohazard types are controlled by various rock deformation types,and the lithologic association has constrained their size.Interbedded sand-slate controlled by brittle bending has often experienced toppling-drawing breakage-slippage-unstable failure-river blockage,and the multistage slope evolution represents the main geohazard model in Yajiang area.