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工程科学与技术:2024,56(1):160-168
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固–液相变含水率区间松散土石体中细粒组分抗剪特性试验
(1.长江水利委员会长江科学院 水利部岩土力学与工程重点实验室,湖北 武汉 430010;2.长江水利委员会长江科学院 信息中心,湖北 武汉 430010;3.中交第二公路勘察设计研究院有限公司,湖北 武汉 430056)
Experimental Study on Shear Characteristics of Fines Component in Loose Deposits with the Water Content Range of Solid-Liquid Phase Change
(1.Key Lab. of Geotechnical Mechanics and Eng. of Ministry of Water Resources, Changjiang River Scientific Research Inst., Wuhan 430010, China;2.Info. Center, Changjiang River Scientific Research Inst., Wuhan 430010, China;3.CCCC Second Highway Consultants Co., Ltd., Wuhan 430056, China)
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投稿时间:2023-05-11    
中文摘要: 松散土石体在泥水作用下易引发地质灾害,其中细粒组分在高含水率下的抗剪性能骤然劣化是触发相变失稳的重要因素之一。基于环剪试验,对三峡库区某滑坡松散土石体试样设计试验方案,研究细组构由软塑~流塑发展的固–液相变全过程抗剪特性演化规律。结果表明:松散土石体试样为粗细组分二元特征较强的级配不良土体介质,其中,细粒组分在原状干密度条件下的饱和含水率为23.6%,液塑限分别为27.2和18.1,据此选定含水率23.6%~29.0%范围中的5个取值制定试验方案,可完整覆盖细粒组分的软塑~流塑相变;含水率为25.0%、26.0%和27.0%时,试样处软塑状态,在低法向压力下均可顺利开展环剪试验;其中,含水率25.0%试样恰进入软塑态,较含水率23.6%试样的峰值和残余内摩擦角分别降低23.5%和18.6%,峰值和残余黏聚力均降低超过80%。含水率为28.0%和29.0%时,试样已处于流塑状态,仅在无法向压力时可顺利开展环剪试验,且抗剪强度极低,其物理意义贴近于高黏稠泥浆的黏滞性;根据试样的黏聚力c在进入软塑状态时基本丧失,而内摩擦角$\varphi $表现为在软塑区间随含水率增加而逐步降低,进而触及液限骤然丧失的特性分析,c和$\varphi $劣化过程异步;经单元体受力模式和概化分析认为,相变前软塑状态试样静止侧压力系数K0的激增缓解了$\varphi $值的大幅骤降。
Abstract:The coupling of loose deposits and slurry is easy to trigger geological disasters. The shear strength deterioration of fine components under high water content is one of the most important factors. Based on the ring-shear test, the experimental study on fine components that are taken from a loose deposits in Three Gorges Reservoir area is carried out in the water content range of solid-liquid phase change. The following conclusions can be obtained: The coarse and fine component binary characteristics is significant. The saturated water content ωsr of fine component in undisturbed condition is 23.6%, ωL and ωP are 27.2 and 18.1 respectively, and the tests conducted in range of ω=23.6%~29.0% could cover the whole phase transformation process; Ring-shear test could be successfully carried out in water content conditions of 25.0%, 26.0% and 27.0%, which are all in soft plastic status. When ω=25.0%, the sample just enters soft plastic state. Compared with ωsr=23.6%, the peak and residual internal friction angle are reduced by 23.5% and 18.6% respectively, while cohesion is reduced by more than 80%, which can be regarded as basic loss; When ω exceeds ωL and achieves 28.0% and 29.0%, ring-shear test can only be carried out at σ=0 kPa, and the shear strength is extremely low, while the physical meaning of this shear strength is closer to viscosity of very viscous mud; Referencing to the water content range involved in this study, cohesion c is basically lost when samples enters soft plastic state, while internal friction angle is characterized by gradual decrease with the increase of ω in soft plastic status, but suddenly loses when ω achieves to ωL. The deterioration process of both shear strength parameters are asynchronous. The stress analysis and generalized calculation show that before phase transition, rapidly increase of K0 for samples in soft plastic status effectively alleviates the significant drop of $\varphi $.
文章编号:202300354     中图分类号:TU42    文献标志码:
基金项目:国家自然科学基金项目(51979009);中央级科研院所基本科研业务费项目(CKSF2019191/YT)
作者简介:第一作者:江洎洧(1984-),男,正高级工程师,博士.研究方向:粗粒土力学特性试验及岩土工程数值计算.E-mail:jiangjw1023@163.com
引用文本:
江洎洧,王汉武,黄玲,张静波.固–液相变含水率区间松散土石体中细粒组分抗剪特性试验[J].工程科学与技术,2024,56(1):160-168.
JIANG Jiwei,WANG Hanwu,HUANG Ling,ZHANG Jingbo.Experimental Study on Shear Characteristics of Fines Component in Loose Deposits with the Water Content Range of Solid-Liquid Phase Change[J].Advanced Engineering Sciences,2024,56(1):160-168.