川西泸定昔格达地层黏土岩工程地质特性研究
Engineering Geological Characteristics of Xigeda Formation Claystone in Luding County,Western Sichuan
李祥 1吴瑞安 2郭长宝 2倪嘉伟 3王炀 2李彩虹 3宋德光3
作者信息
- 1. 中国地质科学院地质力学研究所,北京 100081;中国地质大学(武汉)工程学院,湖北 武汉 430074
- 2. 中国地质科学院地质力学研究所,北京 100081;自然资源部活动构造与地质安全重点实验室,北京 100081
- 3. 中国地质科学院地质力学研究所,北京 100081
- 折叠
摘要
昔格达地层作为一类特殊的半成岩,具有"见风成粉,遇水成泥"的特性,是工程地质问题与地质灾害的良好孕生载体.以川西泸定海子坪昔格达地层黏土岩为研究对象,通过X射线衍射、电镜扫描、现场与室内岩土测试,分析了其物质组成、微观结构及力学特性,重点研究水作用下其物理力学性质的变化规律,并与其他地区昔格达地层工程地质特性进行比较分析.研究表明:①海子坪昔格达地层黏土岩主要成分为粉细砂、黏土等细粒物质,由薄层黄色和灰色的黏土岩互层产出,具有近水平层理构造.②黄色和灰色黏土岩的物质组成相同,但占比不同,黄色黏土岩的黏粒含量比灰色黏土岩高约 12%,方解石含量少约 10%,黄色黏土岩的结构更为致密,黏粒间胶结作用更强.③海子坪昔格达地层黏土岩现场实测渗透系数为 3.62×10-4～7.34×10-4 cm/s,介于其他地区昔格达地层的黏土岩类-砂岩类之间,这与其天然节理发育、受扰动极易开裂的特性密切相关.④黄、灰色黏土岩的黏聚力均随含水率增加而降低,且含水率越高,降幅越大,内摩擦角与含水率的关系则表现有所不同.⑤不同地区昔格达地层的力学特性对含水率变化的敏感性具有明显差异,其中泸定海子坪昔格达地层黏土岩的水敏性最为显著.
Abstract
The Xigeda Formation is a special semi-diagenetic,which has the characteristics of"wind-induced powder,water-induced mud",and is a good carrier for engineering geological problems and geological hazards.In this study,the yellow and gray claystone of the Xigeda Formation in Haiziping Village,Luding County,west-ern Sichuan was investigated.Its material composition,microstructure,and mechanical properties were ana-lyzed by X-ray diffraction(XRD),scanning electron microscopy(SEM),field and laboratory geotechnical tests.The variation law of its physical and mechanical properties under the action of water is emphasized,and the en-gineering geological characteristics of the Xigeda Formation are compared and analyzed with those in other re-gions.Based on the above research,some conclusions are as follows.①The Xigeda Formation claystone in Haiziping Village is mainly composed of fine sand,clay,and additional fine-grained materials.It is produced by yellow and gray thin layers interbedding and has a horizontal lamination structure.②Yellow and gray claystone have the same material composition,but material proportions are different.The clay content of yellow claystone is 12%higher than that of gray claystone,and the calcite content is 10%inferior.The microstructure of yellow claystone is denser and cemented with clay particles more strongly.③The permeability coefficient measured on the site of Xigeda Formation claystone in Haiziping Village is 3.62～7.34×10-4 cm/s,which is between clay-stones and sandstones in Xigeda Formation in other regions.The characteristic of its permeability is closely re-lated to the development of natural joints and the characteristic of cracks that is susceptible to disturbance.④The cohesion of yellow and gray claystone decreased with the increase of moisture content,and the higher the moisture content,the greater the decline,but the relationship between internal friction angle and moisture con-tent was different.⑤ The mechanical properties of the Xigeda Formation in different regions and lithology have obvious differences in sensitivity to moisture content changes,among which the mechanical property weaken-ing by the water of the Xigeda Formation claystone in Haiziping Village,Luding County is the most significant.
关键词
昔格达地层/黏土岩/微观结构/工程地质特性/川西地区Key words
Xigeda Formation/claystone/microstructure/engineering geological characteristics/Western Sichuan引用本文复制引用
基金项目
国家自然科学基金项目(42207233)
中国地质调查局项目(DD20221816)
国家重点研发计划项目课题(2021YFC3000505)
出版年
2024
国家科技期刊平台
NSTL
万方数据