金沙江上游白格滑坡黏土化蚀变岩的灾变力学行为研究  

Catastrophic Mechanical Behavior of Clay-altered Rock in the Baige Landslide Upstream of the Jinsha River

作　　者：李金秋[1,2,3] 张永双 任三绍 毕俊擘 LI Jinqiu;ZHANG Yongshuang;REN Sanshao;BI Junbo(Inst.of Hydrogeology and Environmental Geology,Chinese Academy of Geosciences,Shijiazhuang 050061,China;China Univ.of Geosciences,Beijing 100083,China;Key Lab.of Quaternary Chronology and Hydro-Environment Evolution,China Geologic Surveye,Shijiazhuang 050061,China)

机构地区：[1]中国地质科学院水文地质环境地质研究所,河北石家庄050061 [2]中国地质大学,北京100083 [3]中国地质调查局第四纪年代学与水文环境演变重点实验室,河北石家庄050061

出　　处：《工程科学与技术》2024年第3期72-82,共11页Advanced Engineering Sciences

基　　金：中央院所基本科研业务费项目(SK202109);国家自然科学基金重大专项(41941017)。

摘　　要：金沙江构造结合带是典型的板块碰撞作用形成的构造混杂岩带,不仅地质结构复杂,而且发育了工程特性极差的特殊岩土体。本文在金沙江上游白格滑坡成因机理调查与分析过程中,新发现了巨型滑坡体后缘滑壁发育厚度较大、分布较连续的黏土化蚀变岩,是构成滑动带的重要组分。基于相关样品的原位测试和室内系统的物质组成、耐崩解、环形剪切、动三轴等物理力学试验研究,揭示了黏土化蚀变岩的灾变力学特性及其在白格滑坡形成演化中的作用。主要结论如下:1)白格滑坡黏土化蚀变岩是金沙江构造结合带中蛇绿岩蚀变的产物,蚀变程度高,蚀变系数介于0.64~0.86之间,黏土矿物成分以伊利石为主、伊/蒙混层矿物次之,遇水极易崩解,崩解指数达50%以上;2)黏土化蚀变岩中工程性质最差的是蚀变黏土,水和振动荷载作用下剪切强度弱化显著,含水率由10%增至20%后剪切强度降幅达34%,动强度远小于其静强度,并随着振动次数的增加不断降低,蚀变黏土是促进斜坡岩体结构面贯通、破坏的重要因素;3)白格滑坡滑动面的形成受节理结构面与黏土化蚀变岩联合控制,整体上可分为2种模式:黏土化蚀变岩厚层软弱夹层型和充填节理裂隙贯通型;4)金沙江上游发育的不少巨型高位滑坡与黏土化蚀变岩不良工程特性具有密切的关系,岩体结构与特殊岩性的组合是值得关注的区域性易滑地质结构。以上结论对于青藏高原东缘大江大河岸坡稳定性分析和防灾减灾具有较好的启示意义。The Jinsha River’s tectonic junction zone is a typical tectonic melange zone resulting from plate collisions.It boasts a complex geolo-gical structure and hosts unique rock and soil formations with unfavorable engineering properties.Investigating the Baige landslide upstream of the Jinsha River revealed a novel finding:clay-altered rocks,characterized by significant thickness and continuous distribution,were identified on the rear edge of the massive landslide,playing a crucial role in its composition.Through on-site sampling and laboratory experiments encom-passing material composition,disintegration resistance,annular shear,and dynamic triaxial analysis,the catastrophic mechanical behavior of clay-altered rock and its contribution to the formation and evolution of the Baige landslide were elucidated.Key conclusions include:1)The clay-altered rock in the Baige landslide,exhibiting high alteration degrees,results from intense alteration of ophiolite within the Jinsha River's tectonic junction zone.Alteration coefficients range between 0.64 and 0.86,with mineral components predominantly comprising illite,followed by illite/montmorillonite mixed-layer minerals.It demonstrates high susceptibility to disintegration upon contact with water,with a disintegration in-dex surpassing 50%.2)Altered clay exhibits the poorest engineering properties within clay-altered rock formations,with its strength significantly diminished under the influence of water and vibration loads.Increasing water content from 10%to 20%results in a 34%decrease in shear strength.Dynamic strength notably lags behind static strength and diminishes with increasing vibration cycles,playing a pivotal role in facilitat-ing the penetration and failure of slope rock mass structural planes.3)The formation of the Baige landslide's sliding surface is jointly governed by joint structural planes and clay-altered rock,manifesting two predominant modes:thick,soft interlayered clay-altered rock and filling joints and fractures penetrating types.4)The prevalence of

关 键 词：白格滑坡 黏土化蚀变岩 强度弱化 易滑地质结构 控滑作用 

分 类 号：X43[环境科学与工程—灾害防治]