墨脱区域滑坡滑带土矿物谱学特征及其工程意义

利用X射线衍射、X射线荧光光谱及红外吸收光谱对墨脱县北侧和格林村两处洪积扇滑坡面内采集的滑带土样品测试，分析了的主要矿物、黏土矿物的组成和含量及其化学成分。结果表明，滑带土中主要矿物组成受洪积扇组分控制，其黏土矿物含量分别占9%和10%，墨脱县附近滑动面中滑带土样品的黏土矿物含大量的伊利石，反应出该滑坡事件在很短的时间内完成，滑坡体滑动速率非常高;两处滑带土样品的红外吸收光试均未发现CO2-₃，HCO1-₃或C—H等振动相应产生的吸收峰，表明洪积扇滑动之后，滑坡面处于封闭系统，没有力学性质较差的碳酸盐等外来矿物或含腐蚀质的次生黏土沿滑动面充填进去，其结果增加了滑坡体的稳定性;样品中含有一定量的埃洛石，反应了区域洪积扇发育在非常潮湿温暖的环境中，同时封闭体系内滑带土所含的Na₂O和CaO等化学组分不能通过淋滤作用排出，滑坡面内发生强烈的水-岩相互作用，促使其内部的黏土矿物发生伊利石-伊利石/蒙脱石混层-蒙脱石趋势的转化，导致格林村附近滑坡面内的滑带土中含大量后期分解形成的伊利石/蒙脱石混层。该类黏土矿物组合很大程度上降低了滑带的摩擦强度值，从而提高了再次发生滑坡的危险性。

Spectroscopic Characteristics of Minerals in Sliding Zone Soil in Motuo Landslides and Their Engineering Significance

The sliding zone soil of Motuo and GelinLandslides were tested with X‐ray diffraction ,X‐ray fluorescence ,and infra‐red absorption spectra .Its compositins of main minerals and clay minerals ,even the chemical compositions were comprehensively analyzed .The results show that the composition of the main minerals was controlled by alluvial fan composition ,and the con‐tents of clay minerals accounted for 9% and 10% respectively ,with a large number of illitecontained in the sliding zone soilofMo‐tuoLandslide ,which reflects that the landslide had a high slip rate .There were no exotic corbonates minerals or secondary clay minerals contained corrosive substance with poor mechanical properties filled into theslidingplane because of the closed system , based on the infrared absorption spectrum with no peaks arising from CO 2 -3 ,HCO1 -3 or C—H ,as a positive affect result of the stability of these lamdsiles .The samples of sliding zone soil contain a certain amount of halloysite ,reflecting that the landslides in the area of Motuo developed in a very humid and warm environment .With Na2 O and CaO preserved in the closed system ,a large number of illite/montmorillonite mixed layer formed in the sliding zone soilofGelinlandslide due to the strong water‐rock interac‐tion in thesliding plane with the decomposition of illite .The frictional strength of sliding zone was largely reduced due to the clay mineral assemblages ,leading to the activity risk of landslide increasing .