三峡库区软硬互层近水平地层高切坡崩塌研究

由泥、砂岩互层或厚层砂岩夹泥岩等形成的类似“夹心饼干”的软硬互层近水平层状结构边坡，是三峡库区分布较为广泛的一种结构类型边坡。由于泥、砂岩风化速度的不同而产生的崩塌灾害现象是三峡库区最为常见的一种地质灾害，首先，从地形地貌、地层岩性、结构面组合、降雨作用和风化作用等方面对软硬互层高切坡的崩塌形成原因进行研究，软硬岩的差异性风化而造成的软岩空腔和硬岩中的结构面组合是造成崩塌的主要原因；其次，基于野外调查的地质现象分析，得到了软硬互层高切坡崩塌主要有倾倒、滑移、塑流拉裂、悬臂拉裂、错断等破坏机制，并概化出了各类破坏示意图；通过离散元数值模拟，对泥砂岩软硬互层高切坡崩塌的形成破坏过程进行了再现和分析，其破坏过程为泥岩剥落-岩腔-砂岩裂隙张开-危岩体弯曲-倾倒崩塌-堆积坡脚；最后，在三峡库区高切坡各类破坏机制的基础上，提出了相应的处治对策。研究成果对三峡库区高切坡地质灾害的认识和防治有一定的意义。

Research on collapse of high cutting slope with horizontal soft-hard alternant strata in Three Gorges reservoir area

Soft-hard alternant strata slopes formed by the interbedding of sandstone and mudstone or the mudstone imbedded in thick sandstones are distributed widely in the Three Gorges area. Cavities are formed by differential weathering between sandstone and mudstone and they can cause collapse of slopes. Firstly, mechanism of collapse of high slopes is studied from the aspects, such as the topographical features, lithologic characters, combination of structural surfaces, effects of rainfall and the weathering effects. Differential weathering is the main reason for the collapse of high slopes. Secondly, according to field surveys, failure mechanisms of high slope collapse are classified into toppling, sliding, creeping-tension, cantilever-tension and staggered breaking. Sketch maps of failure were generalized according to the failure mechanism. Forming process of collapse is determined by the numerical simulation. The failure process of collapse is mudstone spalling, cavity, sandstone crack opening, tilting of dangerous rock mass, toppling cillapse and rockfall deposite. Lastly, supporting measures were put forward against all the failure modes of high cutting slopes in the Three Gorges area. Research results are significant in the prevention and treatment of geo-hazards of the Three Gorges reservoir area.