三峡库区宝塔坪滑坡形成机制研究

宝塔坪滑坡是三峡库区现有成因复杂的巨型老滑坡之一,长期以来,工程界对其形成机制一直有着不同的认识。通过详细的现场调查和对勘察资料的深入分析,基于滑坡形态和结构特征,进一步探讨了宝塔坪滑坡的形成机制和演化过程。研究发现：滑坡发育受控于巴东组三段泥灰岩内部及其与二段泥岩之间的层间错动带、坡体后部卸荷裂隙带和长江下切提供的高陡临空面。根据巴东组四段紫红色泥岩在滑坡区不同高程的分布和滑坡结构分析,滑坡形成及演化具有典型“多期活动,逐级牵引”模式。该滑坡共分3期活动历史,地质力学模式均为“临空面形成-卸荷裂隙带发育-泥化的层间错动带塑流沉陷-蠕滑拉裂-滑面贯通”。每期活动牵引后部坡体变形,进而重复前一期的变形破坏过程。

Study of formation mechanism of Baotaping landslide in Three Gorges Reservoir region

Baotaping Landslide is one of the giant old landslides caused by complex formation mechanism in the Three Gorges Reservoir Area, and different understandings of its formation mechanism have existed for a long time. Through detailed field survey and deep analysis on the geological information, we made a further study on the formation mechanism as well as the evolution process based on the form and structure characteristics of the landslide. The research findings prove that Baotaping Landslide development is controlled by three factors: the interlayer disturbed belts between the 3rd section of Badong marl group and the marl of 2nd sections, the unloading fractured zone in the back of slope, as well as the high-steep free face caused by the undercutting of Yangtze River. According to the fact that different altitudes of the four sections of purplish red mudstone and the landslide structures, we conclude that the formation and evolution of Baotaping Landslide has a typical mode as "multi-phase activities and progressively traction". The activity history of the landslide can be divided into three phases, and the geological model in each one can be presented in a process that the formation of free face, then development of unloading fractured zone, plastic-flow and subsidence of muddy disturbed belt, creep cracking and the connection of the slip surface at last. Every term mentioned above would cause deformation at the back of the slope and then the previous deformation and destruction process repeats.