青藏高原东北缘新近纪盆地内旋转-平推式滑坡聚集规律与机理研究

发布时间：2018-11-15 11:44

【摘要】：旋转平推式滑坡在世界各地的新近纪盆地内广泛分布,致灾风险极高。在现场调查的基础上,本文系统梳理了该类滑坡在青藏高原东北缘的空间分布和变形方式,通过取样测试与数值模拟计算,探讨了旋转-平推式滑坡近水平滑动带的变形机理。研究表明:(1)旋转平推滑坡集中于青藏高原东北缘新近纪泥岩盆地内,其活动强度受青藏高原隆升的影响,自高原腹地至边缘盆地,滑体体积逐步减小;(2)滑坡均由高黏粒含量、超固结新近纪泥岩组成,趋向剪胀、渐进性破坏。在河流的侵蚀塑造的近水平剪切应力环境下,薄层剪切带内摩擦角小于10°,剪切带内随机排列的黏土颗粒的逐步定向,呈现韧、脆性变形;(3)滑动带的蠕变、裂隙扩展与地下水的增湿加速材料的流变,滑面沿黏粒含量高、碳酸钙含量低的软弱层扩展。滑带内黏土矿物蠕变、裂纹的扩展,导致宏观变形逐步积累,剪切面逐渐形成,是滑坡变形的动力因素之一。
[Abstract]:Revolving flat-push landslide is widely distributed in Neogene basins all over the world, and the risk of disaster is very high. On the basis of field investigation, the spatial distribution and deformation mode of this kind of landslide in the northeastern margin of Qinghai-Xizang Plateau are systematically combed. Through sampling, testing and numerical simulation, the deformation mechanism of the near horizontal slip zone of the rotary and flat type landslide is discussed. The results are as follows: (1) the landslide is concentrated in the Neogene mudstone basin on the northeast margin of the Qinghai-Xizang Plateau, and its activity intensity is affected by the uplift of the Qinghai-Tibet Plateau, and the volume of the slip body decreases gradually from the hinterland of the plateau to the marginal basin; (2) the landslide consists of high clay content, overconsolidated Neogene mudstone, and tends to shear expansion and progressive failure. Under the condition of near-horizontal shear stress formed by river erosion, the internal friction angle of thin layer shear zone is less than 10 掳, and the random arrangement of clay particles in shear zone is gradually oriented, showing ductile and brittle deformation. (3) creep of slip zone, crack propagation and humidification of groundwater accelerate the rheology of the material, and the slip surface propagates along the weak layer with high clay content and low calcium carbonate content. The creep of clay minerals and the propagation of cracks in slip zone lead to the gradual accumulation of macroscopic deformation and the formation of shear plane, which is one of the dynamic factors of landslide deformation.
【作者单位】：中国地质科学院地质力学研究所国土资源部新构造运动与地质灾害重点实验室;北京国道通公路设计研究院股份有限公司;中国地质调查局;
【基金】：中国地质调查局项目(编号1212011220088) 国家自然科学基金项目(编号41402281)联合资助的成果
【分类号】：P642.22

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