黄土坡滑坡的发育历史:坠覆-滑坡-改造

GROWTH HISTORY OF HUANGTUPO LANDSLIDE: DOWN-SLOPE OVERLAPPING-LANDSLIDING-MODIFICATION

长江三峡库区巴东新县城黄土坡是否为古滑坡、滑坡的范围有多大、新滑坡与古滑坡的关系如何等 ,还存在着不同认识 .基于大量的野外观察资料 ,提出了坠覆 -滑坡 -改造多阶段变形、失稳的斜坡演化模式 .认为黄土坡在滑坡以前经历了长期的坠覆作用 ,坠覆包括了倾倒和深层蠕变两种基本的斜坡变形型式 ;坠覆的基础上发生了滑坡 ,造成了台阶状地貌、构造面线与基岩不协调及滑动角砾岩带等现象 ;滑坡形成后受水文、地貌等条件的影响 ,长期经历着小规模滑坡的叠加改造 ,1995年发生的两次滑坡仍是进一步改造的结果 .黄土坡坠覆 -滑坡 -改造这一有机联系的岩质斜坡变形过程的建立 ,使得关于黄土坡的一些重大问题有了比较明确的认识 ,这也为构造学解决斜坡研究中的一些问题提供了一个典范 .

In 1995 two landslides in the Huangtupo slope in the Three Gorges Reservoir region turned into a hot issue among the engineering geologists and the Chinese government. Although many researches have been made into the slope, there are still many controversies over the characteristics of the Huangtupo slope. Is the Huangtupo slope in the new county of Badong, Three Gorges Reservoir region an ancient landslide? If so, what was the scale of this ancient landslide? What is the relationship between the new landslides and the old landslides? The present paper proposes, on the basis of a great number of field observation references, the slope evolutionary pattern of deformation and instability in the multi_stages of down_slope overlapping, landsliding, and modification. Before the landslide, the Huangtupo slope experienced the long_term down_slope overlapping classified as included toppling and deep_seated creeping, two basic slope deformation forms. The Huangtupo landslide, derived from the preceding down_slope overlapping, brought about the step_like landform. The significant evidences for the landslide are the varied attitudes of structural surfaces and lines of outcrops in the slope and the presence of the sliding breccia zones. Since then, the Huangtupo landslide has experienced small_scale overlapping modifications of landslides. The two landslides that occurred in 1995 were the result of the further modification. It is concluded that the rock slope deformation process of down_slope overlapping_landsliding_modification is an organic one. This conclusion presents us with relatively precise understanding of some important issues about the Huangtupo landslide and also with a typical example of the application of the tectonics to the research into slopes.