The interplay between phyllosilicates fabric and mechanical response of deep-seated landslides. The case of El Forn de Canillo landslide (Andorra)
The interplay between phyllosilicates fabric and mechanical response of deep-seated landslides. The case of El Forn de Canillo landslide (Andorra)
复制标题
页硅酸盐结构与深层滑坡的机械响应之间的相互作用。
DOI：
10.1007/s10346-020-01492-6
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发表时间：
2021
期刊：
影响因子：
6.7
通讯作者：
Veveakis, Manolis
中科院分区：
文献类型：
--
作者：
Seguí, Carolina;Tauler, Esperança;Planas, Xavier;Moya, Jose;Veveakis, Manolis
深层滑坡是地球上最具破坏性的自然灾害之一，通常涉及坚硬的岩体在富含层状硅酸盐的弱粘土剪切带上滑动。因此，该剪切带对覆盖层荷载的力学响应对滑坡的稳定性和演化至关重要。我们由此证明，这种力学响应与形成剪切带的粘土矿物的矿物学和微结构密切相关，反之亦然。通过对活动深部滑坡剪切带的矿物学、结构和力学特征的详细描述，我们试图阐明决定大型深部滑坡破坏机制的过程。所选的案例是位于安道尔公国(比利牛斯山脉东部)的El Forn山体滑坡。其剪切带由志留系黑色页岩形成。利用该滑坡岩心样品，进行了矿物学和显微结构分析(XRPD、SEM-EDS和MicroCT)，并结合力学试验(液限、塑限)，研究了剪切带材料的内部结构与其力学响应之间的相互作用。我们的结果表明，材料的最大力学变化发生在剪切带的中心，在那里层状硅酸盐完全平行于剪切方向排列。晶体的排列及其面对面的接触增加了材料的塑性指数，减少了孔隙率。因此，剪切运动重新安排了剪切带内层状硅酸盐颗粒的接触，降低了材料的阻力，促进了覆盖层的滑动。
Deep-seated landslides are among the most devastating natural hazards on earth, usually involving a rigid rock mass sliding over a weak, clayey shear band rich in phyllosilicates. The mechanical response of this shear band to the loading of the overburden is, therefore, critical for the stability and the evolution of a landslide. We hereby show that this mechanical response is strongly associated with mineralogy and microstructure of clay minerals forming the shear band, and vice versa. By presenting a detailed mineralogical, textural, and mechanical characterization of a shear band of an active deep-seated landslide, we attempt to shed light on processes determining the failure mechanism of a large deep-seated landslide. The case study chosen is the El Forn landslide located in Andorra Principality (Eastern Pyrenees). Its shear band is formed of black shales of the Silurian period. Using core samples of this landslide, we have performed mineralogical and microstructural analyses (XRPD, SEM-EDS, and MicroCT), combined with mechanical tests (liquid limit, plastic limit) to study the interplay between the internal texture of the material of the shear band and its mechanical response. Our results show that the highest mechanical alteration of the material occurs at the center of the shear band, where the phyllosilicates are perfectly aligned parallel to the shearing direction. The alignment of the crystals and their face-to-face contact increases the plasticity index of the material and reduces its porosity. Hence, the shearing movement rearranges the contacts of the phyllosilicate grains inside the shear band, reducing the resistance of the material and promoting the slip of the overburden.
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