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摩岗岭滑坡位于泸定县境内的大渡河右岸一级支流磨西河口,为18世纪四川西部强震诱发的巨型地震高位滑坡.研究揭示,该滑坡发育于高烈度区的康定杂岩中,河谷走向与区域最大主应力方向垂直,河谷下切过程中斜坡经历了强烈的浅表生卸荷回弹,形成高陡斜坡后,谷坡在河谷应力场(重力场)的长期作用下坡体浅表层沿与缓倾坡外的结构面、走向北北西的陡倾结构面(与坡面走向一致)分别发生滑移和拉裂,当河谷切穿得妥断裂后,断裂带塑性变形,牵动上部坡体表层发生压缩-剪胀错动变形;周期性强震的反复作用,滑移和拉裂成脉动式和累进性式发展,最终使上述两组结构面接近贯通状态,上下游北东和北向侧裂面的切割,为坡体大规模失稳奠定了基本条件.1786年强烈的地震、高位地形放大效应、背坡效应等因素叠加最终触发摩岗岭滑坡的发生.
The Mogangling landslide is located at the Moxihekou, a tributary of the right bank of the Dadu River in Luding County and is a giant earthquake-induced landslide triggered by a strong earthquake in western Sichuan in the 18th century. The study reveals that the landslide is developed in the Kangding complex, The direction of the valley is perpendicular to the direction of the maximum principal stress in the area. The slope undergoes a strong superficial unloading rebound during the cutting process of the valley. After the formation of a high-steep slope, the slopes of the valley slope are shallow under the long-term action of the stress field (gravitational field) in the valley The surface slips and pulls along steeply inclined structural planes (consistent with the slope) along the structural plane outside the gentle slope and north and west, respectively. When the valley is properly pierced, the fracture plastic deformation will affect the upper part The compressional-dilatational deformation occurs on the surface of the slope body; the repeated actions of periodic strong earthquakes, the development of pulsation and delamination into pulsation and progressive development finally make the above two structural planes close to the through state, The cutting to the north side of the fractures lays the basic conditions for the large-scale slope instability.The superposition of 1786 strong earthquakes, high-level relief effects and back slope effect finally trigger the occurrence of the Mogangling landslide.