广西碎屑岩典型区域软弱夹层强度特性及其对边坡稳定性影响研究

发布时间：2018-01-12 09:10

本文关键词：广西碎屑岩典型区域软弱夹层强度特性及其对边坡稳定性影响研究　出处：《广西大学》2017年硕士论文　论文类型：学位论文

【摘要】：研究软弱夹层土在不同因素影响下的强度变化,对于广西含软弱夹层碎屑岩边坡稳定性的分析、判别和边坡防护具有至关重要的作用。本论文依托广西壮族自治区国土资源厅重大科研课题“广西碎屑岩地区地质灾害在线预警技术研究”,以典型区碎屑岩边坡中的软弱夹层土为研究对象,开展了夹层土物理性质、三个因素影响(含水率、细粒含量、干湿循环次数)下强度及相应指标的变化、固结剪切蠕变等试验研究,探讨其强度的变化规律,并在此基础上进行含软弱夹层碎屑岩边坡稳定性的数值模拟,以反映夹层土不同强度状态对边坡稳定性影响的规律。主要研究内容和成果如下:1.广西碎屑岩区工程地质条件研究。首先对广西碎屑岩分布、碎屑岩区滑坡发育特征、软弱夹层的类型等进行研究,在此基础上选取广西百色市西林县作为典型研究区,探究了软弱夹层发育的地质基础,阐明了软弱夹层具有的潜在危害,并对碎屑岩软弱夹层土的强度变化规律进行了全面的理论分析,为后续试验提供理论指导。2.广西西林县碎屑岩边软弱夹层土物理力学性质试验研究。利用基本物理性质试验和X射线衍射试验,得出软弱夹层土具有粘土矿物含量高、水稳性差、遇水易软化等特点,室内直剪试验表明含水率、细粒含量和干湿循环次数均会不同程度的降低软弱夹层土的强度,其中含水率影响最为显著。3.广西西林县碎屑岩边软弱夹层土长期强度特性研究。利用ZLB-1型三联流变仪对软弱夹层土展开剪切蠕变试验研究,得到全过程蠕变曲线、“分别加载”蠕变曲线和应力应变等时曲线等分析曲线,并确定了软弱夹层土的长期强度。结果表明广西西林县碎屑岩软弱夹层土蠕变特征明显,曲线以非线性方式发展,剪应力水平越大,稳定蠕变阶段的蠕变速率越大,位移也越大,稳定所需要的时间增加。天然状态下,不同垂直压力下软弱夹层土的长期强度较峰值强度有较大折损,折损率在52.12%～55.29%,说明长期荷载会严重降低软弱夹层土的抗剪强度,实际工程中应充分重视因软弱夹层蠕变特性而产生的强度折损问题。4.广西西林县碎屑岩边软弱夹层土不同强度状态下边坡稳定性数值模拟研究。利用Geo-Studio数值分析软件计算不同软弱夹层土强度状态下含软弱夹层碎屑岩边坡的稳定性,分析认为因含水率、细粒含量、干湿循环及蠕变的变化而带来的软弱夹层土强度损失,会直接导致碎屑岩边坡稳定性的降低,一定条件下引发边坡滑动破坏。碎屑岩边坡稳定性,随软弱夹层含水率增加边坡稳定性呈反S型曲线降低;细粒含量和干湿循环次数的增加,会导致碎屑岩边坡稳定性以指数方式衰减;软弱夹层的蠕变特性会严重削弱边坡的稳定性,常导致边坡突发性的失稳破坏。
[Abstract]:This paper studies the strength change of soft intercalated soil under the influence of different factors, and analyses the stability of clastic rock slope with weak intercalation in Guangxi. Discrimination and slope protection play an important role. This paper relies on the important scientific research project of Guangxi Zhuang Autonomous region Department of Land and Resources "early warning technology of geological hazards in Guangxi clastic rock area". Taking the weak intercalated soil in the clastic rock slope in typical area as the research object, the change of strength and corresponding indexes under the influence of three factors (moisture content, fine grain content, dry-wet cycle times) was carried out. The stability of clastic rock slope with weak intercalation is simulated on the basis of experimental study on consolidation shear creep and so on. The main contents and results are as follows: 1. Engineering geological conditions of clastic rock area in Guangxi. First, the distribution of clastic rock in Guangxi. Based on the study of the characteristics of landslide development and the types of weak intercalation in clastic rock area, Xilin County, Baise City, Guangxi is selected as the typical research area, and the geological basis of the development of weak intercalation is explored. The potential harm of weak intercalation is clarified, and the law of strength variation of clastic rock soft intercalation soil is analyzed theoretically. To provide theoretical guidance for subsequent tests .2. physical and mechanical properties of clastic rock edge soft intercalation soil in Xilin County, Guangxi, using basic physical properties test and X-ray diffraction test. It is concluded that the soft intercalated soil has the characteristics of high clay mineral content, poor water stability and easy softening when treated with water. The direct shear test in laboratory shows that the water content is high. The content of fine particles and the number of dry and wet cycles can reduce the strength of weak intercalated soil in varying degrees. Among them, the effect of water content is the most significant. 3. The long-term strength characteristics of soft intercalated soil with clastic rock edge in Xilin County, Guangxi. Shear creep test of soft intercalated soil is carried out by using ZLB-1 triple rheometer. The creep curves of the whole process, the creep curves of "separate loading" and the isochronous curves of stress and strain are obtained. The long-term strength of soft intercalation soil is determined. The results show that the creep characteristics of clastic rock soft intercalation soil in Xilin County Guangxi are obvious. The curve develops in a nonlinear manner and the shear stress level increases. The greater the creep rate and the greater the displacement, the longer the time required for stability. In natural conditions, the long-term strength of weak intercalated soils under different vertical pressures is more damaged than the peak strength. The reduction rate is 52.12 and 55.29, which indicates that the long-term load will seriously reduce the shear strength of weak intercalated soil. In practical engineering, due attention should be paid to the problem of strength loss caused by creep characteristics of weak intercalation. (4) numerical simulation of slope stability under different strength states of clastic rock edge soft intercalation soil in Xilin County, Guangxi. Geo is used. -Studio numerical analysis software is used to calculate the stability of clastic rock slope with weak intercalation under different strength states of soft intercalated soil. It is concluded that the strength loss of soft intercalated soil caused by the change of moisture content, fine grain content, dry and wet cycle and creep will directly lead to the decrease of the stability of clastic rock slope. The stability of clastic rock slope decreases with the increase of moisture content of weak intercalation. The increase of fine grain content and dry-wet cycle times will lead to the slope stability of clastic rock decays exponentially. The creep property of weak intercalation will seriously weaken the stability of slope and often lead to sudden failure of slope.
【学位授予单位】：广西大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TU457

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