不同吸力下伊犁河谷原状非饱和黄土强度特性试验研究  

STUDY ON THE STRENGTH CHARACTER TEST OF UNDISTURBED UNSATURATED LOESS IN ILI BASIN UNDER DIFFERENT MATRIC SUCTIONS

作　　者：伊学涛 尚彦军[1,2,3] 孟庆森 孟和 崔振东 贺强[4] YI Xuetao;SHANG Yanjun;MENG Qingsen;MENG He;CUI Zhendong;HE Qiang(Key Laboratory of Shale Gas and Geoengineering,Institute of Geology and Geophysics,Chinese Academy of Sciences,Beijing 100029,China;College of Earth and Planetary Sciences,University of Chinese Academy of Sciences,Beijing 100049,China;Xinjiang Key Laboratory of Geohazard Prevention(Xinjiang Institute of Engineering),Urumqi 830023,China;Xinjiang Uygur Autonomous Region Institute of Geological Environment Monitoring,Urumqi 830011,China)

机构地区：[1]中国科学院地质与地球物理研究所,中国科学院页岩气与地质工程重点实验室,北京100029 [2]中国科学院大学,地球与行星科学学院,北京100049 [3]新疆地质灾害防治重点实验室(新疆工程学院),乌鲁木齐830023 [4]新疆维吾尔自治区地质环境监测院,乌鲁木齐830011

出　　处：《工程地质学报》2024年第3期760-771,共12页Journal of Engineering Geology

基　　金：第二次青藏高原综合科学考察研究项目(资助号:2019QZKK0904);第三次新疆综合科学考察项目(资助号:2022xjkk1305).

摘　　要：西风带影响下的伊犁河谷黄土分布广泛,黄土滑坡等灾害十分发育。研究不同吸力下伊犁河谷的非饱和黄土抗剪强度及变形特性,对地质灾害防治具有重要意义。本研究以新疆伊犁河谷的原状黄土为研究对象,开展矿物成分分析和物理性质测试,并利用非饱和土应力-应变控制式三轴仪,对黄土的原状样进行了控制净围压和吸力为常数的固结不排水剪切试验,分析非饱和黄土的强度特性。研究结果表明:(1)在试验测定的基质吸力范围内,净围压越高,试样应力-应变曲线的硬化特征越明显,试样在剪切过程中基本表现为鼓胀变形;在高基质吸力条件下,应力-应变曲线趋向于软化型,试样易出现剪切破坏。(2)试样体应变的变化受净围压和基质吸力的影响。随净围压的增大,体应变趋向于剪缩状态;在较高的基质吸力条件下,体应变的峰值剪胀量越大,剪胀特征也越强。(3)基质吸力影响非饱和黄土的抗剪强度参数。试样黏聚力随基质吸力的增大,表现出良好的线性增长趋势。而试验中基质吸力对内摩擦角的影响程度相对较低,随基质吸力的增大,粉质黏土土样内摩擦角的增长速率逐渐减小至0,内摩擦角值趋于稳定;而粉土土样内摩擦角无明显变化。本研究可为伊犁河谷黄土滑坡等灾害的研究提供力学参数和理论依据。Loess is widely distributed in the Ili Basin,affected by the westerlies,and loess landslides are highly developed.Studying the shear strength and deformation characteristics of unsaturated loess in the Ili Basin under different matric suctions is of great significance.In this paper,undisturbed loess from the Ili Basin in Xinjiang was taken as the study object,and mineral formation analysis and physical property tests were conducted.The consolidated undrained shear test with controlled net confining pressure and constant matric suctions was carried out on the loess samples from the Ili Basin using the Model TFB-1 unsaturated soil stress-strain controlled triaxial test apparatus.The results show that:(1)In the range of matric suction measured by the test,the higher the net confining pressure,the more obvious the hardening characteristics of the stress-strain curve of the sample,and the sample basically shows bulging deformation during the shear process.Under conditions of high matric suction,the stress-strain curves tend to exhibit a softened mode,and the samples are prone to shear failure.(2)The sample s volumetric strain is affected by net confining pressure and matric suction.With an increase in net confining pressure,the volumetric strain tends to shrink.Under conditions of higher matric suction,the peak dilatancy of the volumetric strain is larger,indicating stronger dilatancy characteristics.(3)Matric suction affects the shear strength parameters of unsaturated loess.The cohesion of the two kinds of samples showed a good linear growth trend with the increase in matric suction.The effect of matric suction on the internal friction angle is relatively low.With the increase in matric suction,the growth rate of the internal friction angle of silty clay samples decreases and tends to 0,while the internal friction angle of silty samples shows no evident change.The experimental results of this study can provide mechanical parameters and theoretical support for the study of the formation mechanism of loess landslides

关 键 词：非饱和土 基质吸力 抗剪强度 变形特征 伊犁河谷 

分 类 号：P642.3[天文地球—工程地质学]